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My Indispensable Lotus Notes & Domino Books
Domino System Administration (New Riders Professional)Domino System Administration (New Riders Professional) by Rob Kirkland
Buy new: £36.50 / Used from: £3.69
The ultimate reference book for administrators. You MUST own a copy.
Lotus Notes and Domino 5 Development UnleashedLotus Notes and Domino 5 Development Unleashed by Steven Kern
Buy used from: £0.78
Currently the best Domino development manual.
Lotus Notes & Domino Essential Reference (The Essential ReferenceSeries)Lotus Notes & Domino Essential Reference (The Essential ReferenceSeries) by Tim Bankes
Buy new: £35.69 / Used from: £0.01
A stunning reference book which is just that - REFERENCE! Don't try to read it - it hurts a lot.
Lotus Domino Administration  in a Nutshell: A Desktop Quick Reference (In a Nutshell (O'Reilly))Lotus Domino Administration in a Nutshell: A Desktop Quick Reference (In a Nutshell (O'Reilly)) by Greg Neilson
Buy new: £17.50 / Used from: £11.29
A nice little quick-reference guide.
JavaScript: The Definitive Guide (Definitive Guides)JavaScript: The Definitive Guide (Definitive Guides) by David Flanagan
Buy used from: £3.91
Good general reference book for Javascript.
Java in a Nutshell (In a Nutshell (O'Reilly))Java in a Nutshell (In a Nutshell (O'Reilly)) by David Flanagan
Buy new: £21.87 / Used from: £1.03
Good general reference book for Java.
Practical LotusScriptPractical LotusScript by Anthony Patton
Buy used from: £46.95
A rarity - a LotusScript book!
Lotus Notes and Domino R6 Development UnleashedLotus Notes and Domino R6 Development Unleashed by Steven Kern
Buy new: £43.99 / Used from: £12.35
Published by Sams but badged as IBM... it's pretty good too.