@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/