Miller, R. D., & Hamak, J. E. (1990). Helium resources of the United States, 1989. U.S. Dept. of the Interior, Bureau of Mines.
Lua i Stíl Chicago (17ú heag.)Miller, Richard D., agus John E. Hamak. Helium Resources of the United States, 1989. [Washington, D.C.]: U.S. Dept. of the Interior, Bureau of Mines, 1990.
Lua MLA (9ú heag.)Miller, Richard D., agus John E. Hamak. Helium Resources of the United States, 1989. U.S. Dept. of the Interior, Bureau of Mines, 1990.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.