The cathedral of Cologne, its history, architecture, decorations, art-treasures and legends : a guide for visitors, compiled from historical and descriptive records ... / by Frz. Theo. Helmken ; translated from the german by capt. J. W. Watkins ..
. – Cologne : J. and W. Boisserée, 1889
. – [8], 126, [2] p. ; 18 cm