APA (7th ed.) Citation

Wielen, R. (1979). The density-wave theory confronted by observations. The large-scale characteristics of the galaxy.

Chicago Style (17th ed.) Citation

Wielen, Roland. "The Density-wave Theory Confronted by Observations." The Large-scale Characteristics of the Galaxy 1979.

MLA (9th ed.) Citation

Wielen, Roland. "The Density-wave Theory Confronted by Observations." The Large-scale Characteristics of the Galaxy, 1979.

Warning: These citations may not always be 100% accurate.