Gaya APA

Downs, Robert B. (2004). Books at Changed The World . USA: Signet classic.

Gaya Chicago

Downs, Robert B. Books at Changed The World. USA: Signet classic, 2004. Text.

Gaya MLA

Downs, Robert B. Books at Changed The World. USA: Signet classic, 2004. Text.

Gaya Turabian

Downs, Robert B. Books at Changed The World. USA: Signet classic, 2004. Print.