Goebel, K., Sachs, J., Garnsey, H. E. F., & Balfour, I. B. (1887). Outlines of classification and special morphology of plants. Clarendon Press.

Goebel, K., Julius Sachs, Henry E. F. Garnsey, and Isaac Bayley Balfour. Outlines of Classification and Special Morphology of Plants. Oxford: Clarendon Press, 1887.

Goebel, K., et al. Outlines of Classification and Special Morphology of Plants. Clarendon Press, 1887.