On the systematic position of Hemitrapa and some other Fossil Trapa

GAMS, H. (1927). Die Gattung Trapa L. Die Pflanzenareale I Reihe Heft 3.

GLUCK, H. (1940). Die Gattung Trapella. Bot. Jahrb. 71:267-336.

HEER, O. (1869). Fossile Flora von Alaska. Konigl. Akad. d. Wiss:38.

HONDA, M. & SAKISAKA (1930). Systema Plantarum Japonicarum (jap): 378-379.

KRYSHTOFOVIC, A. N. (1929). Evolution of the Tertiary flora in Asia. New Phyt. 28: 303-312.

MENZEL, P. (1906). Uber die Flora der Sanften-berger Braunkohlen Ablagerungen: 114-119.

MIKI, S. (1937). The water phanerogams in Japan, with special reference of those of Prov. Yamashiro (jap).

Idem (1939). On the remains of Pinus trifolia n. sp. in the upper Tertiary from Central Honshu in Japan. Bot. Mag. Tokyo. 53:239-246.

Idem (1941). On the change of flora in Eastern Asia since Tertiary Period (1). The clay or lignite beds flora in Japan with special reference to the Pinus trifolia beds in Central Hondo. Jap. Journ. Bot. 41:289.

Idem (1948). For the systematic position of Hemitrapa and some fossil Trapa (jap.). Bot. Mag. Tokyo.61:74-77.

NAKANO, H. (1913). Beitrage zur Kenntnis der Variation von Trapa in Japan. Bot. Jahrb. 50: 440-453.

NATHORST, A. G. (1888). Zur fossilen Flora Japans. Palaeont. Abhandl. 4:20-21.

OKUTSU, H. (1939). Fossil Trapas in Japan with the description of 2 new species (jap.). Geol. Soc. Japan. 46: 328-329.

OLIVER, F. W. (1888). On the structure, development and affinities of Trapella Oliv. a new genus of Pedalineae. Ann. Bot. 2:75-115.