Gaya APA
U.S. National report 1981-1990. (1991).
Viena:
IUGG.
Gaya Chicago
U.S. National report 1981-1990.
.
Viena:
IUGG,
1991.
Text.
Gaya MLA
U.S. National report 1981-1990.
.
Viena:
IUGG,
1991.
Text.
Gaya Turabian
U.S. National report 1981-1990.
Viena:
IUGG,
1991.
Print.