@article{GDZPPN001258613, title = {Fields of tangent sets and Hofmann cones.}, journal = {Semigroup forum}, volume = {33}, year = {1986}, pages = {1-28}, zbl = {0619.22007}, url = {http://dml.mathdoc.fr/item/GDZPPN001258613} }
Lawson, J.D. Fields of tangent sets and Hofmann cones.. Semigroup forum, Tome 33 (1986) pp. 1-28. http://gdmltest.u-ga.fr/item/GDZPPN001258613/