grammatical number - What is the correct plural form for multiple bachelor degrees?

I am helping a former intern ready their resume for distribution. The candidate used an abbreviation I was unfamiliar with:

B.S.s in Physics, Computer Science, and Mathematics

I am familiar with the student's educational background so after a moment of thought realized "B.S.s" was their attempt to indicate multiple bachelor of science degrees. That said I can see those unfamiliar with the student's background being confused. Unfortunately, I do not know how to provide the correct punctuation to indicate the correct grammatical number for multiple degrees in the same discipline.

What is the correct plural form for multiple bachelor degrees? Additionally, are there variations for other degree levels: associates, masters, Ph.D, etc.? In addition to the abbreviation what's the correct way to indicate plurality for the unabbreviated form?

Answer

I think this may be one of the rare cases where 's is used to denote plurality:

B.S.'s

This seems to be supported by a bunch of places:

and many more.