Citazione APA

Croft, H. T., Falconer, K. J., & Guy, R. K. (1991). Unsolved problems in geometry. Springer-Verlag.

Stile di citazione Chicago

Croft, Hallard T., K. J. Falconer, e Richard K. Guy. Unsolved Problems in Geometry. New York: Springer-Verlag, 1991.

Citazione MLA

Croft, Hallard T., et al. Unsolved Problems in Geometry. Springer-Verlag, 1991.