I'm not sure, but would "menciona a Shakespeare" be a more or less exact translation of "zitiert Shakespeare" or "quotes from Shakespeare"?

I would understand your sentence as:
He often mentions Shakespeare.

I translated the german sentence:

Er zitiert oft Shakespeare = Cita/menciona a menudo a Shakespeare, I would say.

"Quotes from" would be "zitiert aus" = "citar de", but I wouldn´t use "citar de" in spanish.

What do you think?

I believe the German "zitiern" has to be translated by a different word than "mencionar", because "mencionar" has other equivalents in German.

By "zitieren" you mean he mentions whole texts by Shakespeare. But by saying "El menciona a Shakespeare" you simply say that he mentions Shakespeare, and it isn't the case in German.

Is there another possibility in Spanish for "to cite someone" or "to cite from someone's works"?

I'm pretty sure the best verb would be "citar"
"Él cita a menudo a Shakespeare."
:3

Hi ildefonk,
I also believe that an accurate translation from German would be:
Él cita a menudo a Shakespeare.

bump :)