How to pronounce “grossmann” in English

Without Grossmann's help, Einstein would not have been able to do it.

And Einstein went to Grossmann and said, you've got to tutor me.

So what is it that Grossmann taught to Einstein?

Happily, one of his best friends from university was Marcel Grossmann, who had become an expert in geometry, who was a mathematician.

But happily, a friend of his, Marcel Grossmann, a friend of his from university, had become an expert in it.