Roth Course in Mental Power: Clear Thinking, Memory, Quick Decision, and Good Judgement in Business and Everyday Life. Co-authors Karl V.S. Howland and Frederick Houk Law. Published by Independent Corporation, 1921. 17 issues with issue 18 missing. 24 to 40 pages. 9 1/2" x 6 1/4". Issue one has three tiny tears along bottom edge o/w Fine. Issues five and seven have bottom spine ends rubbed o/w Fine. All other issues are Fine with clean texts. Scarce set with only one booklet missing.