00288nam a2200121Ia 4500082001700000100002200017245004200039260002800081300001500109490003200124500000500156700000500161  a516bM389.OC  aMaruyama, Masaki.  aOn classification of ruled surfacesb  aTokyobKinokuniyac1970  a75p. Bibl.  aLectures in Mathematicsv 3  a  a