Author's Das hängende Dach, 1954.

Information from 678 converted Dec. 19, 2014 (Dr.)

New York times (online), viewed Mar. 11, 2015 (in obituary published Mar. 10: Frei Otto; b. Frei Paul Otto, May 31, 1925, Siegmar, near Chemnitz; d. Monday [Mar. 9, 2015], Germany, aged 89; architect and engineer known for creating dazzling tensile structures that inspired generations of architects to dangle roofs from poles and cables)