"H.M.V. Gramophones 1921 to 1936" - Barry A. Williamson - Phonoservice - Published in 1999
A smashing little book aimed at providing details of model numbers and identification details for owners. Obviously not as comprehensive as Brian Oakley and Christopher Proudfoot's later book but never the less an interesting source of information in the form of reproduced catalogue illustrations from the period.
"Some Gramophones of the 1920's" - Barry A. Williamson - Phonoservice - Published in 1995
A bit of a coffee table book this one full of contemporary adverts, catalogue information etc. A book to dib into over a cuppa.
"Old Gramophones And Other Talking Machines"- Ben Bergonzi - Shire Publications - First published 1991: My edition was 2000.
Only 32 pages long but packed with information and black and white photographs especially useful for those new to gramophones. Ben Bergonzi was at one time Curator of the Artefacts at the British Library National Sound Archive. Though out of print as far as I know new copies are still available. I paid £3 for a mint new copy so beware anyone charging substantially more than this.