%0 Journal Article %A Allan J. Sieradski %A Michael N. Dyer %T Trees of Homotopy Types of Two-Dimensional CW-Complexes %J Commentarii mathematici Helvetici %D 1973 %P 31-44 %V 48 %I mathdoc %U http://geodesic.mathdoc.fr/item/CMH_1973__48_139535/ %F CMH_1973__48_139535