The hottest book about China right now is Jung Chang and Jon Halliday’s Mao: The Untold Story. In that big, much praised and much condemned biography, the Long March of 1935 takes up about fifty out of 800 pages.
For decades, the main source for the epoch of the March was the account Mao Zedong gave to the American journalist Edgar Snow, author of Red Star over China. Published in 1938, after careful editing by Mao himself, this narrative underlies all the subsequent accounts in Chinese and Western biographies of Mao and more general histories. The story was given further wings in 1985 by another American journalist, Harrison Salisbury, in his The Long March.