APA

Dressel W. M., Volosin J. S., . (1984). Inverted pyramid-shaped plugs for closing abandoned mine shafts. Washington, DC: US Dep. of the Interior, Bureau of Mines.

Chicago

Dressel Waldemar M, Volosin John S, . 1984. Inverted pyramid-shaped plugs for closing abandoned mine shafts. Washington, DC: US Dep. of the Interior, Bureau of Mines.

Harvard

Dressel W. M., Volosin J. S., . (1984). Inverted pyramid-shaped plugs for closing abandoned mine shafts. Washington, DC: US Dep. of the Interior, Bureau of Mines.

MLA

Dressel Waldemar M, Volosin John S, . Inverted pyramid-shaped plugs for closing abandoned mine shafts. Washington, DC: US Dep. of the Interior, Bureau of Mines. 1984.