Calderón was awarded a Rockefeller Scholarship to enable him to undertake research at the University of Chicago and this he did, having Zygmund supervise his doctorate which was awarded in 1950.
Calderón ay iginawad isang Rockefeller Scholarship na paganahin sa kanya upang magsagawa ng pananaliksik sa University of Chicago at siya na ito ay, sa pagkakaroon ng Zygmund-asikaso ng kanyang titulo ng doktor na kung saan ay iginawad sa 1950.