Gaya APA
Virts, William B.. (1987).
Purchasing / William B. Virts .
USA,:
.
Gaya Chicago
Virts, William B..
Purchasing / William B. Virts.
USA,:
,
1987.
Text.
Gaya MLA
Virts, William B..
Purchasing / William B. Virts.
USA,:
,
1987.
Text.
Gaya Turabian
Virts, William B..
Purchasing / William B. Virts.
USA,:
,
1987.
Print.