Gaya APA
Gerber, Philip L.. (1979).
Effective english .
United States of America:
Silver Burdett Company.
Gaya Chicago
Gerber, Philip L..
Effective english.
United States of America:
Silver Burdett Company,
1979.
Text.
Gaya MLA
Gerber, Philip L..
Effective english.
United States of America:
Silver Burdett Company,
1979.
Text.
Gaya Turabian
Gerber, Philip L..
Effective english.
United States of America:
Silver Burdett Company,
1979.
Print.