The major tactics of chess: a treatise on evolutions; the proper employment of the forces in strategic, tactical, and logistic planes (1898)
Young, Franklin Knowles, 1857- · Boston, Little, Brown and company · leaf 106
81 STRATEGIC PLANES. A Point of Impenetrability is any point in the Objec- tive Plane which in a given situation is occupied by an adverse piece other than the King. A POINT OF IMPENETRABILITY. FIGURE 69. Black. … Whitr.
Chess
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