@article{10_4153_CJM_1995_039_0,
     author = {Fowler, Neal J.},
     title = {Free {E} {0-Semigroups}},
     journal = {Canadian journal of mathematics},
     pages = {744--785},
     year = {1995},
     volume = {47},
     number = {4},
     doi = {10.4153/CJM-1995-039-0},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1995-039-0/}
}