APA

Howden H. F., .Speculations on some beetles, barriers, and climates during the pleistocene and Pre-pleistocene periods in some nonglaciated portions of North America. : .

Chicago

Howden Henry F, .Speculations on some beetles, barriers, and climates during the pleistocene and Pre-pleistocene periods in some nonglaciated portions of North America. : .

Harvard

Howden H. F., .Speculations on some beetles, barriers, and climates during the pleistocene and Pre-pleistocene periods in some nonglaciated portions of North America. : .

MLA

Howden Henry F, .: . .