(2 customer ratings) ★★★★★
After Tarbell finished his 60 lesson Tarbell Course he decided to continue with post-graduate lessons. The name post-graduate stems from the fact that Tarbell sent out graduation diplomas for all who followed along his 60 lesson course. To my knowledge he only published one such post-graduate lesson. If you know about more such lessons I would be delighted to hear from you.
1st edition, 1926, Tarbell System Inc., Chicago; 33 pages.