Brown & Sharpe "Formulas in Gearing - with Practical Suggestions" a Comprehensive 266-page text book covering every gear type. Every calculation carefully explained with useful suggestions. The preface say s: "This book deals with the subject of gearing, essentially from the designer's and draftsman's standpoint. It's aim is to condense as much as possible the solution of all problems in gearing which in ordinary practice may be met with......the mathematics employed are simple,and will present no difficulty to anyone familiar with ordinary algebra, the elements of trigonometry and logarithms