- Harold van der Heijden's database of chess studies, Endgame Study Database 2015 can be purchased from his website Harold van der Heijden Database V 2015.
But any PGN-file with studies can be used.
- A tool by Emil Vlasák that makes CQL easier to use, is available from Visual CQL.
- The given examples can be downloaded as a CQL_Examples.zip from here or copied from the example-pages.
- The introduction article by Gady Costeff can be downloaded from here: chess_query_language.pdf .