Töpffer published seeral more of these books, and wrote theoretical essays on the form.

"Reference group theory with implications for information studies: a theoretical essay."

The journal contains theoretical essays, case studies, and review essays.

Throughout his career he published important theoretical essays and books on art.

But in his theoretical essays he gives some interesting indications of the ways in which they may contribute to a poem's effect.

The answers received varied from lengthy and highly theoretical essays to more direct comments.

Kandinsky's detailed theoretical essays described the correlations between color and sound.

Some practical problem questions, other theoretical essays, much like legal philosophy type essays.

A book of theoretical essays, Reinventing Africa, appeared in 1998.