Simon Brett and Len Tyler have suggested the following pre-conference reading for their talk on The Changing Image of the Golden Age. Some of these are articles and not a book so a careful internet search may prove fruitful in locating copies (possibly, though by no means caertainly, for free).

The Simple Art of Murder by Raymond Chandler

The Golden Age of Murder by Martin Edwards

Murder for Pleasure by Howard Haycraft

Talking About Detective Fiction by P.D. James

Bloody Murder by Julian Symons

Snobbery with Violence by Colin Watson

Who Cares Who Killed Roger Ackroyd? by Edmund Wilson

The Baffle Book by Lassiter Wren and Randle McKay