APA (7th ed.) Citation

Pyper, N. C., Essex, D. W., & Whelan, C. T. (2001). The 1s2 1s2p(1P) excitation energy for helium atoms in liquid helium, solid helium and helium bubbles in metals. Philosophical Magazine B, 81(1), 91. https://doi.org/10.1080/13642810010007467

Chicago Style (17th ed.) Citation

Pyper, N. C., D. W. Essex, and Colm T. Whelan. "The 1s2 1s2p(1P) Excitation Energy for Helium Atoms in Liquid Helium, Solid Helium and Helium Bubbles in Metals." Philosophical Magazine B 81, no. 1 (2001): 91. https://doi.org/10.1080/13642810010007467.

MLA (9th ed.) Citation

Pyper, N. C., et al. "The 1s2 1s2p(1P) Excitation Energy for Helium Atoms in Liquid Helium, Solid Helium and Helium Bubbles in Metals." Philosophical Magazine B, vol. 81, no. 1, 2001, p. 91, https://doi.org/10.1080/13642810010007467.