PETRICK, J. A. (1966). Energy resource assessment - Alfred Petrick JR. Westview Press.
Lua i Stíl Chicago (17ú heag.)PETRICK, JR. Alfred. Energy Resource Assessment - Alfred Petrick JR. Westview Press, 1966.
Lua MLA (8ú heag.)PETRICK, JR. Alfred. Energy Resource Assessment - Alfred Petrick JR. Westview Press, 1966.
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