We shouldn’t take writing credits from those sources.
The purpose of those sources is to know who to send royalties to, not to reproduce artistic credits from booklets.
When a band chooses to credit band, those sources will split credits to each credit, which is not correct as A, B, C and D did not write lyrics in fact and they all did not write music either, not necessarily.
When a song falls into public domain after some years, the original credits may be replaced by P.D./D.P. in those sources