"drawings on prison walls"
"drawing bought from a homeless person at the train station for 10 marks."
"drawing made under the influence of LSD"
Treasures from the university library: Between all the shiny art books I found this rather plain looking publication: Zeichnung Heute (Drawing Today), which was published on the occasion of an exhibition with the same name in Vienna in 1971.
The book is full of examples for all different ways drawings are used. The last page is blank and visitors of the exhibition could make their own drawings and participate in the show.