APA
(1981). Proceedings of the national academy of sciences. U. S. A: National Academy Of Science.
Chicago
1981. Proceedings of the national academy of sciences. U. S. A: National Academy Of Science.
Harvard
(1981). Proceedings of the national academy of sciences. U. S. A: National Academy Of Science.
MLA
Proceedings of the national academy of sciences. U. S. A: National Academy Of Science. 1981.