APA
Gottschalk Walter Helbig, Heldund Gustav Arnold, . (1955). Topological dynamics. : .
Chicago
Gottschalk Walter Helbig, Heldund Gustav Arnold, . 1955. Topological dynamics. : .
Harvard
Gottschalk Walter Helbig, Heldund Gustav Arnold, . (1955). Topological dynamics. : .
MLA
Gottschalk Walter Helbig, Heldund Gustav Arnold, . Topological dynamics. : . 1955.
