When checkmating with bishop and knight against a lone king, a king can be checkmated only in a corner of the bishop's colour. Jesús de la Villa, 100 Endgames You Must Know
If we are considering sacrificing a bishop in an attack on the king, we must be sure that our knight(s) can cooperate effectively with our queen. David LeMoir, Essential Chess Sacrifices
Having seized the initiative it is essential to develop it with all means at your disposal, not fearing either material or positional losses. Valeri Beim, Lessons In Chess Strategy
A good knowledge of the standard attacking and defensive ideas is required to play sharp openings successfully. James Rizzitano, Understanding Your Chess
In major-piece-endings, king safety and the initiative are the critical factors, more than material advantage. Steve Giddins, 50 Essential Chess Lessons