Lucio Fontana - Graphics, Multiples and more, Camillo Rigo and Harry Ruhé, Tuja Books 2006, p. 140, numbers B-3 and B-4.
The sculptures B-3 and B-4 together form a set. They are casts of terracotta sculptures dating from 1959.
Concetto spaziale, Natura, 1968, bronze (two pieces), with brown patina, each monogrammed L. F. in the cast, numbered no. 65 of 90 copies