F4, Feature Films, 1941–1950 (1997) F6, Feature Films, 1961–1970 (1976) Due to the large number of co-productions between American and foreign companies in the 1960s, and the difficulty of determining any particular film's nationality, this volume includes all feature films released theatrically in the United States in that period. The hardcover edition includes pornographic features, although they have been excluded from the electronic database edition. Errors in the print editions have been carried over to the online version, despite published criticisms, and there is no means by which users can offer discussions or corrections.