APA (7th ed.) Citation
Bes, D. R., Dussel, G. G., & Sofía, H. M. (1977). Normalization of states in perturbation theories. American Association of Physics Teachers.
Chicago Style (17th ed.) Citation
Bes, D. R., G. G. Dussel, and H. M. Sofía. Normalization of States in Perturbation Theories. American Association of Physics Teachers, 1977.
MLA (9th ed.) Citation
Bes, D. R., et al. Normalization of States in Perturbation Theories. American Association of Physics Teachers, 1977.
Warning: These citations may not always be 100% accurate.