00326nam a2200121 a 4500041000800000082001800008100001800026245007800044260003600122300001000158650002200168650001400190  aeng  a300.1bN14s77  aNagel, Ernest  aThe structure of sciencebproblems in the logic of scientific explanation  aNew YorkbHarcourtbBracec1961  a618 p  aCIENCIAS SOCIALES  aFILOSOFIA