Inconsistent & vs. and.
Gratuitous references to common knowledge which you tracked down as a form of procrastination (e.g. Petri 1887).
Obvious misplaced fields in electronic database citation collection.
Commas instead of semicolons, or similar format errors.
Mixed formats in bibliography.
Autoformatting that undoes manual corrections.
Crummy old Xerox copies which cut off the journal information.
Bibliography references orphaned by aggressive cuts.
References missing from the bibliography because they are only listed in figure captions, which is a different file.
Subtle misplaced fields in electronic database citation collection (e.g. page and volume numbers switched).
Correcting a reference database error in the proof, without fixing the database.
References written in non-latin alphabets.
Drain the bottle:
Referenced papers you’ve never actually read.
My reference formatter is set up perfectly, I have no need to look at the output.
Software updates delete all the corrections you performed to your reference list.
Actually reading the referenced paper only to find that it actually says the opposite of what you inferred based on the way that other people referenced it.
Monday, November 08, 2010