00350nam a2200109Ia 4500008004100000082001900041100001900060245005700079260003100136300001500167440005800182260720b        |||||||| |||| 00| 0 eng d  a530.1bP417.TD  aPenrose, Roger  aTechniques of differential topology in relativityb/  aPhiladelphia:bSIAM,c1972  aviii, 72p.  aRegional conference series in Applied Mathematics ; 7