APA (7th ed.) Citation

Frobel, F., Michaelis, E., & Moore, H. K. (1891). Froebel's letters on the kindergarten. Swan Sonnenschein.

Chicago Style (17th ed.) Citation

Frobel, Friedrich, Emilie Michaelis, and H. Keatley Moore. Froebel's Letters on the Kindergarten. London: Swan Sonnenschein, 1891.

MLA (8th ed.) Citation

Frobel, Friedrich, et al. Froebel's Letters on the Kindergarten. Swan Sonnenschein, 1891.