His Master's Degree was achieved with a thesis in quasianalytic functions, then he became interested in operator theory which came out of earlier work he had done on the moment problem.
Kanyang Master's Degree ay makakamtan sa pamamagitan ng isang tesis sa quasianalytic function, at pagkatapos, siya ay naging interesado sa operator ng teorya na nagmula sa labas ng mas maaga ang trabaho niya tapos na sa sandali ng problema.