Joseph Nedava: Arthur Koestler (London: R. Anscombe, 1948) Joseph Nedava had been a follower of Jabotinsky and of the Irgun, and was contacted by Koestler in his covert meetings with the Palestine underground in the '40s. It is one of the first critics to have studied Koestler, and one of the very few that stressed the importance of Koestler's Jewish background.
John Atkins: Arthur Koestler (London: Neville Spearman Ltd, 1956) The first major book-length study on Koestler, written by John Atkins, a british-born academic who taught in the Sudan. Now quite outdated and very focused on the problem (that had been Koestler's main problem in those years) of the fate of Europe facing Soviet Union.
Murray A. Sperber (ed.): Arthur Koestler - A Collection of Critical Essays (Prentice-Hall 1977) I