APA (7th ed.) Citation

Beard, B. L., Johnson, C. M., & Cox, L. (1999). Iron isotope biosignatures. Science, 285(5435), 1889. https://doi.org/10.1126/science.285.5435.1889

Chicago Style (17th ed.) Citation

Beard, Brian L., Clark M. Johnson, and Lea Cox. "Iron Isotope Biosignatures." Science 285, no. 5435 (1999): 1889. https://doi.org/10.1126/science.285.5435.1889.

MLA (9th ed.) Citation

Beard, Brian L., et al. "Iron Isotope Biosignatures." Science, vol. 285, no. 5435, 1999, p. 1889, https://doi.org/10.1126/science.285.5435.1889.