APA (7th ed.) Citation

Webb, N., Cseh, D., & Kirsten, F. (2014). Variability in ultra-luminous X-ray sources.

Chicago Style (17th ed.) Citation

Webb, N., D. Cseh, and Franz Kirsten. Variability in Ultra-luminous X-ray Sources. 2014.

MLA (9th ed.) Citation

Webb, N., et al. Variability in Ultra-luminous X-ray Sources. 2014.