In the ending one weakness in the opposition camp is seldom enough to win. You need to create a second weakness, and alternate attacks until the defence cannot keep up. John Cox, Starting Out: Alekhine's Defence
The main rationale behind the English is to play either in the centre or on the queenside, but in both cases utilising the control of d5 as a focal point upon which to build one's position. Nigel Povah, How To Play The English Opening
The queen-and-knight combination is often referred to as the deadliest attacking force in chess. The two pieces work so well together because their differing movements complement each other perfectly. John Emms, Starting Out: The Scotch Game
In a pawn ending with pawns on both sides of the board, the most important rule is: the side which has its passed pawn further from the other pawns usually wins. Jesper Hall, Chess Training For Budding Champions
A simple test: have I files for my rooks? If I have, I am sure to have freedom for my other pieces as well. Cecil Purdy, The Search For Chess Perfection