84/90. Edition and signature upper in pencil. Sheet from the series of 8 cretti (7 black and 1 white). Total edition: 90 copies + XV. 2RC Printing House, Rome. Publication: Burri. General catalogue. Graphic work 1949-1994. Ed. coloured. Vol. 5, edited by Chiara Sarteanesi and Bruno Corà, Fond. Pal. Albizzini Col. Burri, 2015, p.78 ill. 21c; Alberto Burri graphic works', San Luca gallery, Bologna, p.37 (another copy); Butters graphics. Complete work', exhibition catalog edited by C. Sarteanesi, Città di Castello 11 October 2003 - 11 January 2004, Silvana Editoriale, 2003, p. 69 (another specimen). Sitography: https://www.2rcgallery.com/edizioni/burri-alberto/#colibri-1961-c5-group-35 . Small defects.