Hello James,
I agree with Owen’s list and don’t think there are any other books I’d add. Many past editions of The Deep Sky Observer (the Webb Society in-house journal) will be found to contain articles on planetaries so it’s well worth joining Webb! Also, if you use the Uranometria star atlas then the associated Deep Sky Field Guide to Uranometria (Willmann-Bell) gives useful short summaries of planetaries appearing in the atlas.
Hope this helps, Stewart