Gaya APA

survey, E, L, G. (1979). preliminary report on a visit to the ombilin coal mines sumatra indonesia january 29-31, 1979 . : prepared under the auspices of the agency of international development u.s depar.

Gaya MLA

survey, E.r, Landis,u,s, Geological. "preliminary report on a visit to the ombilin coal mines sumatra indonesia january 29-31, 1979". : prepared under the auspices of the agency of international development u.s depar, 1979. Text.