Frank, H. J. (1966). Crude oil prices in the Middle East: A study in oligopolistic price behavior. Praeger.
Cytowanie według stylu Chicago (wyd. 17)Frank, Helmut Jack. Crude Oil Prices in the Middle East: A Study in Oligopolistic Price Behavior. New York: Praeger, 1966.
Cytowanie według stylu MLA (wyd. 9)Frank, Helmut Jack. Crude Oil Prices in the Middle East: A Study in Oligopolistic Price Behavior. Praeger, 1966.