APA (7th ed.) Citation

Heintz, K. (2012). Learn about frequency and amplititude, two important qualities of sound. Encyclopedia Britannica.

Chicago Style (17th ed.) Citation

Heintz, Kurt. Learn About Frequency and Amplititude, Two Important Qualities of Sound. Chicago, IL: Encyclopedia Britannica, 2012.

MLA (9th ed.) Citation

Heintz, Kurt. Learn About Frequency and Amplititude, Two Important Qualities of Sound. Encyclopedia Britannica, 2012.