एपीए उद्धरण

Chopra, P. N. (2006). Principles of economics (9th ed.). Kalyani.

शिकागो स्टाइल उद्धरण

Chopra, P. N. Principles of Economics. 9th ed. Ludhiana: Kalyani, 2006.

एमएलए उद्धरण

Chopra, P. N. Principles of Economics. 9th ed. Kalyani, 2006.