Empty reference in https://reactome.org/PathwayBrowser/#DIAGRAM=168255

[egonw]

There is an empty reference at pathway level, with a "0" pubmed identifier and no further info. At least since version 66 and still persistent in Reactome 75.

[egonw]

The reference is a book, and not converted well by the convertor.

[egonw]

Applies to https://www.wikipathways.org/index.php/Pathway:WP5022 and https://www.wikipathways.org/index.php/Pathway:WP2683