I have two mint condition books by John Knibbs (both first editions) that I would like to sell and would appreciate any advice on the current value of them so I can offer them for sale at a fair price.

The first book is a 1986 first edition of "BSA and Lincoln Jeffries Air Rifles". There is a light pencil price written inside the cover that says:- £65. Presumably this is what was paid for it but it is very feint and could easily be removed with a pencil rubber. Other than this small mark the book is in perfect condition and looks like it has never been read.

The second book is a 2002 first edition of "The Golden Century". This book also looks like it has never been read and has no pencil marked price on it

Any helpful advice on realistic current values would be appreciated as I would like to get these two books put up for sale - and hopefully - see them go to a BSA collector/enthusiast who will really appreciate and enjoy having them.