FOREIGN BOOKS (TO 1992). OPENING. MANUALS
"Always take care of the center which should be strong! And it's strong only when it's not subject to danger. It is better to have in the center only one, but fully defended Pawn, than three or four Pawns, defending which gives troubles."
Rudolf Spielman, grandmaster
"A Piece's posting in the center, from where it operates in several directions, may serve as the foundation for making very active plans. Many various ideas and combinations were realized on this basis."
Peter Romanovsky, international master