1. I’m not a graphic designer or a scholar of graphic design.
2. There’s a very big world of typography out there. “Swiss and German design from the mid-20th century” is a teeny-tiny sliver of it, and it’s at the bottom of the list of things I’m interested in.
3. A two-second Google search brought up this and this. If you want to check them out and your essay isn’t due within the next week or so, see if your local public library has them—or if it has access to WorldCat and an interlibrary loan service. (Knowing how to use ILL will serve you very well when you get to college, I promise you.) Also, check the references/bibliographies on the relevant Wikipedia pages, those are full of good primary sources.
There is a Adrian Frutiger book in spanish is called “sobre la tipografía” i dunno if there is a english version. Frutiger itself make an study and comparative in the XVIII,XIX and XX century typefaces and its creators.
If i can give you advise i will start from the modernism-industrialization
with Giambatista bodoni and the “didones” typefaces, later go to the egyptian serif typefaces and to finish with the grotesk typefaces.
in fact modern graphic design ends in the 60s-70 so include a little bit of humanist typefaces such as adrian frtutiger typefaces.