Which preposition to use with alumnus

of Occurrences 14%

I'd like to see what the new preacher is doing, and it ought to be worth something to hear a Negro alumnus of Yale.

from Occurrences 3%

Why then discriminate between alumni from the North and alumni from the South at a gathering in which alumni from both sections are expected to meet?...

for Occurrences 1%

It remains only to thank the alumni for their loyal financial support through the subscription blanks sent out in June, and the library staff of the college for the generosity with which more than the ordinary facilities of the library have been tendered.

Which preposition to use with  alumnus