Hello folks, for a research project I would like to know which was the first font that included a semi-serif version and/or a mixed version (half serif, half sans)

I remember now Rotis from Mr. Aicher or Penumbra from Mr. Hidy. But Im not sure which one was the first that presented this possibility. And of course Thesis...

And second is, if you thing that a semi-serif version really is usefull in the real life (for text for example) or its just a variety used more in titles.

Thanks

Leonardo Vazquez