TY - BOOK ED - Sieradski, Allan J ED - Metzler, Wolfgang ED - Hog-Angeloni, Cynthia TI - Two-dimensional homotopy and combinatorial group theory T2 - London Mathematical Society Lecture Notes Series; no.197 SN - 0521447003 U1 - 514.2 PY - 1993/// CY - Cambridge PB - Cambridge University Press KW - Homotopy Theory KW -