Gaya APA
Earth. (1971).
Singapura:
McGraw-Hill Far Eastern Publishers.
Gaya Chicago
Earth.
.
Singapura:
McGraw-Hill Far Eastern Publishers,
1971.
.
Gaya MLA
Earth.
.
Singapura:
McGraw-Hill Far Eastern Publishers,
1971.
.
Gaya Turabian
Earth.
Singapura:
McGraw-Hill Far Eastern Publishers,
1971.
.