Tobias:
Darryl beat me to the first one, but you should find both these books quite helpful, and the latter one extremely readable:
Franks, Norman, Frank Bailey and Russell Guest. "BLOODY APRIL...BLACK SEPTEMBER. London, Grub Street, 1995. 288 pp., illus.
Morris, Alan.
BLOODY APRIL. London, Jarrolds, 1967. 208 pp., illus.
Best Regards,
Ira