Arthurian Literature in the Middle Ages is a book edited by Roger Sherman Loomis and published by the Clarendon Press at Oxford in 1959. It has become a standard reference work and is often abbreviated as ALMA.
This work was intended as a replacement for the book Evolution of Arthurian Romance from the Beginnings down to the year 1300, published by James Douglas Bruce in 1923. Bruce’s work, although often excellent, paid little attention to very early Arthurian literature or to Arthurian literature arguably written after the year 1300, and sometimes came to idiosyncratic conclusions unacceptable to most Arthurian scholars.
Loomis’ book contains individual chapters each written by a different recognized Arthurian scholar, with Loomis as the editor overseeing it all.
See Roger Sherman Loomis (1959).