APA (7th ed.) Citation

Booch, G., Rumbaugh, J., & Jacobson, I. (1999). Unified (the) Modeling Language User Guide. Addison-Wesley.

Chicago Style (17th ed.) Citation

Booch, Grady, James Rumbaugh, and Ivar Jacobson. Unified (the) Modeling Language User Guide. Addison-Wesley, 1999.

MLA (8th ed.) Citation

Booch, Grady, et al. Unified (the) Modeling Language User Guide. Addison-Wesley, 1999.