added source

README.md

@@ -119,4 +119,5 @@ element Introduction {
 - https://getbootstrap.com/docs/4.0/components
 - https://www.w3schools.com/xml/xpath_intro.asp
 - https://xmlgraphics.apache.org/fop/quickstartguide.html
+- https://xmlgraphics.apache.org/fop/examples.html
 - https://www.kosek.cz/xml/schema/rng.html
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