@article{01959266, title = {On the geometry of intuitionistic S4 proofs.}, journal = {Homology, Homotopy and Applications}, volume = {5}, year = {2003}, pages = {137-209}, zbl = {1022.03010}, language = {en}, url = {http://dml.mathdoc.fr/item/01959266} }
Goubault-Larrecq, Jean; Goubault, Éric. On the geometry of intuitionistic S4 proofs.. Homology, Homotopy and Applications, Tome 5 (2003) pp. 137-209. http://gdmltest.u-ga.fr/item/01959266/