McKenney, F., Jess, Z., & Crukshank, J. (1809). A key to the American tutor's assistant revised: In which all the examples necessary for a learner are wrought at large, and also solutions given of all the questions for exercise in the various rules : designed principally to facilitate the labour of teachers, and assist such as have not the opportunity of a tutor's aid. Philadelphia: Printed by Joseph Crukshank.

McKenney, Frederic., Zachariah Jess, and Joseph Crukshank. A Key to the American Tutor's Assistant Revised: In Which All the Examples Necessary for a Learner Are Wrought At Large, and Also Solutions Given of All the Questions for Exercise in the Various Rules : Designed Principally to Facilitate the Labour of Teachers, and Assist Such As Have Not the Opportunity of a Tutor's Aid. Philadelphia: Printed by Joseph Crukshank, 1809.

McKenney, Frederic., Zachariah Jess, and Joseph Crukshank. A Key to the American Tutor's Assistant Revised: In Which All the Examples Necessary for a Learner Are Wrought At Large, and Also Solutions Given of All the Questions for Exercise in the Various Rules : Designed Principally to Facilitate the Labour of Teachers, and Assist Such As Have Not the Opportunity of a Tutor's Aid. Philadelphia: Printed by Joseph Crukshank, 1809.