Spoken Esperanto :
by the direct method for beginners; a practical manual for teachers, for use with school classes and groups /
compiled and published by Norman W. Frost.

APA Citation

Frost, N. W. (1923). Spoken Esperanto: by the direct method for beginners; a practical manual for teachers, for use with school classes and groups. Cambridge, Mass..

MLA Citation

Frost, Norman W. Spoken Esperanto: by the Direct Method for Beginners; a Practical Manual for Teachers, for Use With School Classes And Groups. Cambridge, Mass., 1923.

Warning: These citations may not always be complete (especially for serials).