[1]
O. B. Bøggild, “J. W. W. Spencer: The Falls of Niagara, their evolution and varying relations to the great lakes; characterics of the power, and the effects of its diversion. Canada Department of Mines, Geol. Surv. Branch, Ottawa 1907 (490 Sider -f 44 Tavler)”., gt, bd. 19, jan. 1908.