एपीए उद्धरण

Helmer, R., & Hespanhol, I. (1997). Water pollution control.

शिकागो स्टाइल उद्धरण

Helmer, Richard, और Ivanildo Hespanhol. Water Pollution Control. London, E and FN Spon, 1997.

एमएलए उद्धरण

Helmer, Richard, और Ivanildo Hespanhol. Water Pollution Control. 1997.