A page from "The Night Hamburg Died", Martin Caidin, Four Square/New English Library, London, 1966. Originally published in USA by Ballatine Books, Inc, 1960

The text below the picture reads:

A building in a Hamburg area were there was not a firestorm. Note the window boxes on the balconies which survived the fire; in the firestorm everything combustible was consumed. National Fire Protection Association

(Note that Caidin has worked for US "intelligence":

In Japan for two years with the Intelligence and Public Information offices of the U.S. 5th Air Force, Mr. Caidin toured the devastated Japanese cities, and spent much time in Hiroshima, where the world's first atomic bomb used in the war was dropped.

ibid., page 157)