Gaya APA
Keller, Edward A.. (1988).
Environmental geology (5th ed).
Columbus:
Merrill.
Gaya Chicago
Keller, Edward A..
Environmental geology.
5th ed
Columbus:
Merrill,
1988.
Text.
Gaya MLA
Keller, Edward A..
Environmental geology.
5th ed
Columbus:
Merrill,
1988.
Text.
Gaya Turabian
Keller, Edward A..
Environmental geology.
5th ed
Columbus:
Merrill,
1988.
Print.