Howard Staunton (1873). “The Chess-player's Handbook: A Popular and Scientific Introduction to the Game of Chess, Exemplified in Games Actually Played by the Greatest Masters, and Illustrated by Numerous Diagrams of Original and Remarkable Positions”, p.34
Joseph Lancaster (1805). “Improvements in Education, as it Respects the Industrious Classes of the Community: Containing Among Other Important Particulars, an Account of the Institution for the Education of One Thousand Poor Children, Borough Road Southwark; and of the New System of Education on which it is Conducted”, p.180