J. Maletz, The identity of Didymograptus (Expansograptus) suecicus (TULLBERG) and related species (Graptoloidea, Dichograptidae), Palaontologische Zeitschrift Palaontologische Zeitschrift (Print);Journal of Palaontologische Gesellschaft Scientific contributions to palaeontology, 70(1/2), 1996, pp. 203-212