(S (S (PP (IN Between) (BASENP (NN 1935) (CC and) (NN 1938))) (COMMA ,) (S (BASENP (PRP he)) (VP (VBD studied) (NP (BASENP (JJ nuclear) (NNS reactions)) (CC and) (BASENP (NN reaction) (NN cross) (NNS sections)))))) (PERIOD .))