Ported the first part of the Depiction chapter

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diff --git a/README.md b/README.md
@@ -2,7 +2,7 @@
 
 # Groovy Cheminformatics with the Chemistry Development Kit
 
-[Edition 2.9-1](https://egonw.github.io/cdkbook/)
+[Edition 2.9-2](https://egonw.github.io/cdkbook/)
 
 **Egon L. Willighagen** PhD<br />
 Long time CDK developer

diff --git a/atomsbonds.md b/atomsbonds.md
@@ -644,6 +644,6 @@ in ring sets, explained in Section ??.
 
 ## References
 
-1. <a name="citeref1"></a>Steinbeck C, Han Y, Kuhn S, Horlacher O, Luttmann E, Luttmann E, et al. The Chemistry Development Kit (CDK): an open-source Java library for Chemo- and Bioinformatics. JCICS. 2003 Feb 11;43(2):493–500.  doi:[10.1021/CI025584Y](https://doi.org/10.1021/CI025584Y) ([Scholia](https://scholia.toolforge.org/doi/10.1021/CI025584Y))
+1. <a name="citeref1"></a>Steinbeck C, Han Y, Kuhn S, Horlacher O, Luttmann E, Willighagen E. The Chemistry Development Kit (CDK): an open-source Java library for Chemo- and Bioinformatics. JCICS. 2003 Feb 11;43(2):493–500.  doi:[10.1021/CI025584Y](https://doi.org/10.1021/CI025584Y) ([Scholia](https://scholia.toolforge.org/doi/10.1021/CI025584Y))
 2. <a name="citeref2"></a>Balaban AT. Applications of graph theory in chemistry. JCICS. 1985 Aug 1;25(3):334–43.  doi:[10.1021/CI00047A033](https://doi.org/10.1021/CI00047A033) ([Scholia](https://scholia.toolforge.org/doi/10.1021/CI00047A033))
 
diff --git a/builders.md b/builders.md
@@ -66,7 +66,7 @@ refactoring to do.
 
 ## Implementations
 
-As indicated earlier, there are various implementations. CDK 2.8
+As indicated earlier, there are various implementations. CDK 2.9
 has three implementations: the default builder, a builder to create debug
 output creating classes, and two builders that create data classes that do
 not send around change events.
@@ -108,11 +108,11 @@ event is when the atom was added, while the second event is caused by the
 element symbol of the atom changing:
 
 ```plain
-Event: org.openscience.cdk.event.ChemObjectChangeEvent[source=AtomContainer(55...
-  9087077, #A:1, AtomRef{Atom(1566104673, S:C, AtomType(1566104673, FC:0, Isot...
-  ope(1566104673, Element(1566104673, S:C, AN:6))))})]
-Event: org.openscience.cdk.event.ChemObjectChangeEvent[source=Atom(1566104673,...
-   S:N, AtomType(1566104673, FC:0, Isotope(1566104673, Element(1566104673, S:N...
+Event: org.openscience.cdk.event.ChemObjectChangeEvent[source=AtomContainer(73...
+  4370487, #A:1, AtomRef{Atom(1091523506, S:C, AtomType(1091523506, FC:0, Isot...
+  ope(1091523506, Element(1091523506, S:C, AN:6))))})]
+Event: org.openscience.cdk.event.ChemObjectChangeEvent[source=Atom(1091523506,...
+   S:N, AtomType(1091523506, FC:0, Isotope(1091523506, Element(1091523506, S:N...
   , AN:7))))]
 ```
 

diff --git a/cheminfo.md b/cheminfo.md
@@ -318,8 +318,8 @@ Kit supports this multidisciplenaire research.
 27. <a name="citeref27"></a>de Jong S. SIMPLS: An alternative approach to partial least squares regression. Chemometr Intell Lab. 1993 Mar;18(3):251–63.  doi:[10.1016/0169-7439(93)85002-X](https://doi.org/10.1016/0169-7439(93)85002-X) ([Scholia](https://scholia.toolforge.org/doi/10.1016/0169-7439(93)85002-X))
 28. <a name="citeref28"></a>Todeschini R, Consonni V. Handbook of Molecular Descriptors. 2000.  doi:[10.1002/9783527613106](https://doi.org/10.1002/9783527613106) ([Scholia](https://scholia.toolforge.org/doi/10.1002/9783527613106))
 29. <a name="citeref29"></a>J. K. Wegner, PhD thesis, Eberhard-Karls-Universität Tübingen, Tübingen, Germany, 2006
-30. <a name="citeref30"></a>Steinbeck C, Han Y, Kuhn S, Horlacher O, Luttmann E, Luttmann E, et al. The Chemistry Development Kit (CDK): an open-source Java library for Chemo- and Bioinformatics. JCICS. 2003 Feb 11;43(2):493–500.  doi:[10.1021/CI025584Y](https://doi.org/10.1021/CI025584Y) ([Scholia](https://scholia.toolforge.org/doi/10.1021/CI025584Y))
-31. <a name="citeref31"></a>Steinbeck C, Hoppe C, Hoppe C, Kuhn S, Floris M, Guha R, et al. Recent Developments of the Chemistry Development Kit (CDK) - An Open-Source Java Library for Chemo- and Bioinformatics. Curr Pharm Des [Internet]. 2006 Jun 1;12(17):2111–20. Available from: https://cdk.github.io/cdk-paper-2/ doi:[10.2174/138161206777585274](https://doi.org/10.2174/138161206777585274) ([Scholia](https://scholia.toolforge.org/doi/10.2174/138161206777585274))
+30. <a name="citeref30"></a>Steinbeck C, Han Y, Kuhn S, Horlacher O, Luttmann E, Willighagen E. The Chemistry Development Kit (CDK): an open-source Java library for Chemo- and Bioinformatics. JCICS. 2003 Feb 11;43(2):493–500.  doi:[10.1021/CI025584Y](https://doi.org/10.1021/CI025584Y) ([Scholia](https://scholia.toolforge.org/doi/10.1021/CI025584Y))
+31. <a name="citeref31"></a>Steinbeck C, Hoppe C, Kuhn S, Floris M, Guha R, Willighagen E. Recent Developments of the Chemistry Development Kit (CDK) - An Open-Source Java Library for Chemo- and Bioinformatics. Curr Pharm Des [Internet]. 2006 Jun 1;12(17):2111–20. Available from: https://cdk.github.io/cdk-paper-2/ doi:[10.2174/138161206777585274](https://doi.org/10.2174/138161206777585274) ([Scholia](https://scholia.toolforge.org/doi/10.2174/138161206777585274))
 32. <a name="citeref32"></a>Kowalski BR. Chemometrics. Anal Chem. 1980 Apr;52(5):112–22.  doi:[10.1021/AC50055A016](https://doi.org/10.1021/AC50055A016) ([Scholia](https://scholia.toolforge.org/doi/10.1021/AC50055A016))
 33. <a name="citeref33"></a>BK L. Chemometrics. Anal Chem. 2000 Jun 1;72(12):91R-97R.  doi:[10.1021/A1000016X](https://doi.org/10.1021/A1000016X) ([Scholia](https://scholia.toolforge.org/doi/10.1021/A1000016X))
 34. <a name="citeref34"></a>Buydens LMC, Reijmers TH, Beckers MLM, Wehrens R. Molecular data-mining: a challenge for chemometrics. Chemometr Intell Lab. 1999 Oct;49(2):121–33.  doi:[10.1016/S0169-7439(99)00039-8](https://doi.org/10.1016/S0169-7439(99)00039-8) ([Scholia](https://scholia.toolforge.org/doi/10.1016/S0169-7439(99)00039-8))

diff --git a/chemobject.md b/chemobject.md
@@ -69,8 +69,8 @@ which outputs:
 
 ```plain
 Number of containers: 2
-container's hashcode 1263085541
-container's hashcode 1281205497
+container's hashcode 32777062
+container's hashcode 1187406578
 ```
 
 The other options is to use a regular for-loop:
@@ -89,8 +89,8 @@ which requires more coding, but has the advantage that it keeps track of the ind
 
 ```plain
 Number of containers: 2
-container 0 has hashcode 632168320
-container 1 has hashcode 1761382759
+container 0 has hashcode 517960153
+container 1 has hashcode 551377008
 ```
 
 ## IReactionSet and IRingSet

diff --git a/code/AtomContainersLoopingInSet.code.md b/code/AtomContainersLoopingInSet.code.md
@@ -20,6 +20,6 @@ for (atomContainer in set.atomContainers()) {
 **Output:**
 ```plain
 Number of containers: 2
-container's hashcode 285831951
 container's hashcode 32777062
+container's hashcode 1187406578
 ```
diff --git a/code/GuessSMILES.code.md b/code/GuessSMILES.code.md
@@ -1,7 +1,7 @@
 # GuessSMILES.groovyl
 **Source code:**
 ```groovy
-@Grab(group='org.openscience.cdk', module='cdk-bundle', version='2.8')
+@Grab(group='org.openscience.cdk', module='cdk-bundle', version='2.9')
 
 import java.io.*;
 import org.openscience.cdk.io.*;

diff --git a/code/ObjectListening.code.md b/code/ObjectListening.code.md
@@ -21,10 +21,10 @@ atom1.setSymbol("N")
 ```
 **Output:**
 ```plain
-Event: org.openscience.cdk.event.ChemObjectChangeEvent[source=AtomContainer(19...
-  63448684, #A:1, AtomRef{Atom(1913714009, S:C, AtomType(1913714009, FC:0, Iso...
-  tope(1913714009, Element(1913714009, S:C, AN:6))))})]
-Event: org.openscience.cdk.event.ChemObjectChangeEvent[source=Atom(1913714009,...
-   S:N, AtomType(1913714009, FC:0, Isotope(1913714009, Element(1913714009, S:N...
+Event: org.openscience.cdk.event.ChemObjectChangeEvent[source=AtomContainer(73...
+  4370487, #A:1, AtomRef{Atom(1091523506, S:C, AtomType(1091523506, FC:0, Isot...
+  ope(1091523506, Element(1091523506, S:C, AN:6))))})]
+Event: org.openscience.cdk.event.ChemObjectChangeEvent[source=Atom(1091523506,...
+   S:N, AtomType(1091523506, FC:0, Isotope(1091523506, Element(1091523506, S:N...
   , AN:7))))]
 ```
diff --git a/code/RenderMolecule.code.md b/code/RenderMolecule.code.md
@@ -0,0 +1,20 @@
+# RenderMolecule.groovy
+**Source code:**
+```groovy
+@Grab(group='org.openscience.cdk', module='cdk-bundle', version='2.9')
+
+import org.openscience.cdk.depict.*;
+import org.openscience.cdk.interfaces.*;
+import org.openscience.cdk.templates.*;
+IAtomContainer triazole = MoleculeFactory.make123Triazole()
+new DepictionGenerator()
+  .withSize(600, 600)
+  .withMargin(0.1)
+  .withZoom(3.0)
+  .withAtomColors()
+  .depict(triazole)
+  .writeTo("RenderMolecule.png");
+```
+**Output:**
+```plain
+```
diff --git a/code/SimpleFingerprintDemo.code.md b/code/SimpleFingerprintDemo.code.md
@@ -1,7 +1,7 @@
 # SimpleFingerprintDemo.groovyl
 **Source code:**
 ```groovy
-@Grab(group='org.openscience.cdk', module='cdk-bundle', version='2.8')
+@Grab(group='org.openscience.cdk', module='cdk-bundle', version='2.9')
 
 import org.openscience.cdk.interfaces.*;
 import org.openscience.cdk.templates.*;

diff --git a/code/TPSACalc.code.md b/code/TPSACalc.code.md
@@ -29,7 +29,7 @@ value = result.getValue()
 ```
 **Output:**
 ```plain
-Specification: org.openscience.cdk.qsar.DescriptorSpecification@369ad7da
+Specification: org.openscience.cdk.qsar.DescriptorSpecification@3e98b933
 Parameters names: [checkAromaticity]
 Parameters values: [false]
 Exception: null

diff --git a/depiction.md b/depiction.md
@@ -0,0 +1,60 @@
+<a name="sec:ch:depiction"></a>
+# Depiction
+
+The CDK originates from the merger of Jmol and <a name="tp1">JChemPaint</a> [<a href="#citeref1">1</a>]. As such, CDK has long
+contained code to depict molecules. However, after the 1.0 series, a rewrite of the code base
+was initiated, causing the CDK 1.2 series to not be available with <a name="tp2">rendering</a> functionality.
+During the development of the 1.4 series, the rendering code became gradually available as
+a set of patches, and, separately, as a JChemPaint applet. The new rendering code has
+entered the CDK.
+
+However, if you need rendering of reaction schemes or the editing functionality found
+in JChemPaint, you still need the <a name="tp3">CDK-JChemPaint</a> patch.
+
+## Molecules
+
+Rendering molecules to an image is done in a few steps. First, an `Image` needs
+to be defined, for example, of 200 by 200 pixels. The next step is to define what is to be
+generated, and how. The most basic rendering requires a few generators: one for the overall
+scene, one for atoms, and one for bonds. Therefore, we add a [`BasicSceneGenerator`](http://cdk.github.io/cdk/latest/docs/api/org/openscience/cdk/renderer/generators/BasicSceneGenerator.html),
+a [`BasicAtomGenerator`](http://cdk.github.io/cdk/latest/docs/api/org/openscience/cdk/renderer/generators/BasicAtomGenerator.html), and a [`BasicBondGenerator`](http://cdk.github.io/cdk/latest/docs/api/org/openscience/cdk/renderer/generators/BasicBondGenerator.html).
+We will see later that we can add further generators to add further visualization.
+Now that we defined what we want to have depicted, we construct a renderer. Because we
+are rendering a molecule here, we simply use the [`AtomContainerRenderer`](http://cdk.github.io/cdk/latest/docs/api/org/openscience/cdk/renderer/AtomContainerRenderer.html).
+
+<a name="fig:fig:triazole"></a>
+![](images/generated/RenderMolecule.png)
+<br />**Figure 16.1**: 2D diagram of triazole
+
+We also need to define, however, what rendering platform we want to use. The Java
+community has a few options, with the AWT/Swing platform to be the reference implementation
+provided by Oracle, and the SWT toolkit as a popular second. In fact, the redesign
+was needed to be able to support both widget toolkits. For rendering images,
+we can use the AWT toolkit. Therefore, we use a [`AWTFontManager`](http://cdk.github.io/cdk/latest/docs/api/org/openscience/cdk/renderer/font/AWTFontManager.html) to help the
+renderer draw texts. We get our `Graphics2D` object to which will be drawn from the
+earlier created image, and we set some basic properties.
+Then we are ready to draw the molecule to the graphics object with the `paint()`
+method, and here again we need a AWT-specific class: the [`AWTDrawVisitor`](http://cdk.github.io/cdk/latest/docs/api/org/openscience/cdk/renderer/visitor/AWTDrawVisitor.html).
+
+What then remains is to save the image to a <a name="tp4">PNG</a> image file with the
+`ImageIO` helper class.
+
+The full code example then looks like:
+
+**Script** [code/RenderMolecule.groovy](code/RenderMolecule.code.md)
+```groovy
+new DepictionGenerator()
+  .withSize(600, 600)
+  .withMargin(0.1)
+  .withZoom(3.0)
+  .withAtomColors()
+  .depict(triazole)
+  .writeTo("RenderMolecule.png");
+```
+
+This results in the image of triazole given in Figure [16.1](#fig:fig:triazole).
+
+## References
+
+1. <a name="citeref1"></a>Krause S, Willighagen E, Steinbeck C. JChemPaint - Using the Collaborative Forces of the Internet to Develop a Free Editor for 2D Chemical Structures. Molecules. 2000 Jan 28;5(1):93–8.  doi:[10.3390/50100093](https://doi.org/10.3390/50100093) ([Scholia](https://scholia.toolforge.org/doi/10.3390/50100093))
+
diff --git a/descriptor.md b/descriptor.md
@@ -61,7 +61,7 @@ allowing one to mix descriptor calculation by various tools and to keep
 track of what value came from what vendor.
 
 For example, we can inspect these field values for the TPSA descriptor
-(see Section [17.3](properties.md#sec:tpsa)):
+(see Section [18.3](properties.md#sec:tpsa)):
 
 **<a name="script:TPSASpecs">Script 17.1</a>** [code/TPSASpecs.groovy](code/TPSASpecs.code.md)
 ```groovy
@@ -80,7 +80,7 @@ Title: org.openscience.cdk.qsar.descriptors.molecular.TPSADescriptor
 Reference: http://www.blueobelisk.org/ontologies/chemoinformatics-algorithms/#...
   tpsa
 Vendor: The Chemistry Development Kit
-Identifier: 2.8
+Identifier: 2.9
 ```
 
 The identifier values originally referred to a String which held the
@@ -126,7 +126,7 @@ descriptor.parameterNames.each { name ->
 }
 ```
 
-which tells us how we can tune the descriptor calculation (see also Section [18.5](#sec:noCount)):
+which tells us how we can tune the descriptor calculation (see also Section [19.5](#sec:noCount)):
 
 ```plain
 elementName -> java.lang.String
@@ -178,11 +178,11 @@ java.lang.Boolean -> true
 With this information about the descriptor now clear, it is time to look at a descriptor
 value calculation. A molecular descriptor in the CDK is symbolized by the
 [`IMolecularDescriptor`](http://cdk.github.io/cdk/latest/docs/api/org/openscience/cdk/qsar/IMolecularDescriptor.html) interface, which extends the [`IDescriptor`](http://cdk.github.io/cdk/latest/docs/api/org/openscience/cdk/qsar/IDescriptor.html) interface,
-as shown in Figure [18.1](#fig:descriptorInheritance).
+as shown in Figure [19.1](#fig:descriptorInheritance).
 
 <a name="fig:descriptorInheritance"></a>
 ![](images/descriptor.png)
-<br />**Figure 18.1**: The IDescriptor interface has a few derived interfaces, but only IMolecularDescriptor is shown here.
+<br />**Figure 19.1**: The IDescriptor interface has a few derived interfaces, but only IMolecularDescriptor is shown here.
 
 The relevant method now is the `calculate(IAtomContainer)` method, which returns
 a [`DescriptorValue`](http://cdk.github.io/cdk/latest/docs/api/org/openscience/cdk/qsar/DescriptorValue.html). This class is returned rather than a double, because descriptors
@@ -207,7 +207,7 @@ value = result.getValue()
 The output shows us that quite some metadata is preserved:
 
 ```plain
-Specification: org.openscience.cdk.qsar.DescriptorSpecification@241fc278
+Specification: org.openscience.cdk.qsar.DescriptorSpecification@3e98b933
 Parameters names: [checkAromaticity]
 Parameters values: [false]
 Exception: null
@@ -262,14 +262,14 @@ Calculated values: 7
 ```
 
 The [`IDescriptorResult`](http://cdk.github.io/cdk/latest/docs/api/org/openscience/cdk/qsar/result/IDescriptorResult.html) interface is currently implemented by various classes,
-outlined in Figure [18.2](#fig:descriptorResults). Each of the classes has a slightly different
+outlined in Figure [19.2](#fig:descriptorResults). Each of the classes has a slightly different
 API to get the actual values. The [`IntegerResult`](http://cdk.github.io/cdk/latest/docs/api/org/openscience/cdk/qsar/result/IntegerResult.html), [`DoubleResult`](http://cdk.github.io/cdk/latest/docs/api/org/openscience/cdk/qsar/result/DoubleResult.html),
 and [`BooleanResult`](http://cdk.github.io/cdk/latest/docs/api/org/openscience/cdk/qsar/result/BooleanResult.html) classes have the methods `intValue()`,
 `doubleValue()`, and `booleanValue()` respectively.
 
 <a name="fig:descriptorResults"></a>
 ![](images/descriptorResults.png)
-<br />**Figure 18.2**: The IDescriptorResults interface has several implementation, each wrapping calculated descriptor values.
+<br />**Figure 19.2**: The IDescriptorResults interface has several implementation, each wrapping calculated descriptor values.
 
 The two array variants, [`IntegerArrayResult`](http://cdk.github.io/cdk/latest/docs/api/org/openscience/cdk/qsar/result/IntegerArrayResult.html) and [`DoubleArrayResult`](http://cdk.github.io/cdk/latest/docs/api/org/openscience/cdk/qsar/result/DoubleArrayResult.html),
 work slightly different, and both provide a `get(int)` method to iterate over all
@@ -334,7 +334,7 @@ the case for all descriptors, but many take this approach.
 ## References
 
 1. <a name="citeref1"></a>Wikberg J, Eklund M, Willighagen E, Spjuth O, Lapins M, Engkvist O, et al. Introduction to Pharmaceutical Bioinformatics. 2018. 
-2. <a name="citeref2"></a>Steinbeck C, Hoppe C, Hoppe C, Kuhn S, Floris M, Guha R, et al. Recent Developments of the Chemistry Development Kit (CDK) - An Open-Source Java Library for Chemo- and Bioinformatics. Curr Pharm Des [Internet]. 2006 Jun 1;12(17):2111–20. Available from: https://cdk.github.io/cdk-paper-2/ doi:[10.2174/138161206777585274](https://doi.org/10.2174/138161206777585274) ([Scholia](https://scholia.toolforge.org/doi/10.2174/138161206777585274))
+2. <a name="citeref2"></a>Steinbeck C, Hoppe C, Kuhn S, Floris M, Guha R, Willighagen E. Recent Developments of the Chemistry Development Kit (CDK) - An Open-Source Java Library for Chemo- and Bioinformatics. Curr Pharm Des [Internet]. 2006 Jun 1;12(17):2111–20. Available from: https://cdk.github.io/cdk-paper-2/ doi:[10.2174/138161206777585274](https://doi.org/10.2174/138161206777585274) ([Scholia](https://scholia.toolforge.org/doi/10.2174/138161206777585274))
 3. <a name="citeref3"></a>Guha R, Howard MT, Hutchison GR, Murray-Rust P, Rzepa HS, Steinbeck C, et al. The Blue Obelisk-interoperability in chemical informatics. JCIM. 2006 Feb 22;46(3):991–8.  doi:[10.1021/CI050400B](https://doi.org/10.1021/CI050400B) ([Scholia](https://scholia.toolforge.org/doi/10.1021/CI050400B))
 4. <a name="citeref4"></a>Spjuth O, Willighagen E, Guha R, Eklund M, Wikberg J. Towards interoperable and reproducible QSAR analyses: Exchange of datasets. J Cheminform. 2010;2(1):5.  doi:[10.1186/1758-2946-2-5](https://doi.org/10.1186/1758-2946-2-5) ([Scholia](https://scholia.toolforge.org/doi/10.1186/1758-2946-2-5))
 5. <a name="citeref5"></a>[https://stackoverflow.com/questions/9363550/how-to-prevent-getting-a-groovy-boolean-in-an-object-array](https://stackoverflow.com/questions/9363550/how-to-prevent-getting-a-groovy-boolean-in-an-object-array)

diff --git a/graph.md b/graph.md
@@ -268,7 +268,7 @@ Another important aspect of the chemical graph, is that the graph uniquely
 places atoms in the molecule. That is, the graphs allows us to uniquely
 identify, and therefore, number atoms in the molecule. This is an important
 aspect of cheminformatics, and the concept behind <a name="tp13">canonicalization</a>, such
-as used to create <a name="tp14">canonical SMILES</a>. The InChI library (see Chapter [19](inchi.md#sec:inchi))
+as used to create <a name="tp14">canonical SMILES</a>. The InChI library (see Chapter [20](inchi.md#sec:inchi))
 implements such an algorithm, and we can use it to assign unique integers to all
 atoms in a chemical graph.
 

diff --git a/images/generated/CTR2.png b/images/generated/CTR2.png
diff --git a/images/generated/FixPyrroleBondOrders.png b/images/generated/FixPyrroleBondOrders.png
diff --git a/images/generated/InChIAtomNumbers.png b/images/generated/InChIAtomNumbers.png
diff --git a/images/generated/InChIAtomNumbersBenzene.png b/images/generated/InChIAtomNumbersBenzene.png
diff --git a/images/generated/MethaneExplicit.png b/images/generated/MethaneExplicit.png
diff --git a/images/generated/MethaneImplicit.png b/images/generated/MethaneImplicit.png
diff --git a/images/generated/RenderAdenine.png b/images/generated/RenderAdenine.png
diff --git a/images/generated/RenderAdenineWithNumbers.png b/images/generated/RenderAdenineWithNumbers.png
diff --git a/images/generated/RenderMolecule.png b/images/generated/RenderMolecule.png
diff --git a/images/generated/RenderOxazole.png b/images/generated/RenderOxazole.png
diff --git a/images/generated/StereoisomerOne.png b/images/generated/StereoisomerOne.png
diff --git a/images/generated/StereoisomerTwo.png b/images/generated/StereoisomerTwo.png
diff --git a/inchi.md b/inchi.md
@@ -115,7 +115,7 @@ one mobile hydrogen to the second atom, which is the first oxygen.
 <!-- <code>RenderAdenine</code> -->
 <a name="fig:adenine"></a>
 ![](images/generated/RenderAdenine.png)
-<br />**Figure 19.1**: 2D diagram of one of the tautomers of adenine.
+<br />**Figure 20.1**: 2D diagram of one of the tautomers of adenine.
 
 ### Stereoisomerism