APA (7th ed.) Citation

Burkhalter + Sumi, Widder, L., Burkhalter, M., Sumi, C., & Helfenstein, H. (1999). Marianne Burkhalter + Christian Sumi. Birkhäuser.

Chicago Style (17th ed.) Citation

Burkhalter + Sumi, Lynnette Widder, Marianne Burkhalter, Christian Sumi, and Heinrich Helfenstein. Marianne Burkhalter + Christian Sumi. Basel [etc.]: Birkhäuser, 1999.

MLA (9th ed.) Citation

Burkhalter + Sumi, et al. Marianne Burkhalter + Christian Sumi. Birkhäuser, 1999.