Gear design simplified a series of gear-designing charts illustrating by simple diagrams and examples the solutions of practical problems relating to spur gears, straight-tooth bevel gears, spiral-bevel gears, helical gears for parallel shaft drives, helical (spiral) gears for angular drives, heringbone gears, and worm gears - Jones, Franklin Day 1879-1967; Ryffel, Henry H. 1920-2012 (Industrial Press, 1961)