APA (7th ed.) Citation

Frolich, P. K. (1944). Petroleum, past, present & future. [publisher not identified].

Chicago Style (17th ed.) Citation

Frolich, Per Keyser. Petroleum, Past, Present & Future. [Place of publication not identified]: [publisher not identified], 1944.

MLA (9th ed.) Citation

Frolich, Per Keyser. Petroleum, Past, Present & Future. [publisher not identified], 1944.

Warning: These citations may not always be 100% accurate.