APA (7th ed.) Citation

Krukoff, B. A., Monachino, J., & Barneby, R. C. Supplementary notes on the American species of Strychnos.

Chicago Style (17th ed.) Citation

Krukoff, B. A., J. Monachino, and Rupert C. Barneby. Supplementary Notes on the American Species of Strychnos.

MLA (9th ed.) Citation

Krukoff, B. A., et al. Supplementary Notes on the American Species of Strychnos.