M. N. G James, G. J. B Williams (1974). «A Refinement of the Crystal Structure of Maleic Acid». Acta CrystallographicaB30 (5) (5): 1249–1275. doi:10.1107/S0567740874004626.
Kurt Lohbeck, Herbert Haferkorn, Werner Fuhrmann and Norbert Fedtke "Maleic and Fumaric Acids" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2000.