00320nam a2200097Ia 4500008004100000082002200041100003300063245007200096260004600168300000800214140113s9999    xx            000 0 und d  a378(047)(73)   K9  aNational Academy of Sciences  aInvisible University : post doctoral education in the United States  a1969bNational Academy of SciencecU.S.A.  a310