@article{10_1017_S0017089500008442,
     author = {Jones, Peter R. and Margolis, Stuart W. and Meakin, John and Stephen, Joseph B.},
     title = {Free products of inverse semigroups {II}},
     journal = {Glasgow mathematical journal},
     pages = {373--387},
     year = {1991},
     volume = {33},
     number = {3},
     doi = {10.1017/S0017089500008442},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500008442/}
}