@article{10_1017_S0017089500031232,
     author = {Easdown, David and Gould, Victoria},
     title = {Orders in power semigroups},
     journal = {Glasgow mathematical journal},
     pages = {39--47},
     year = {1996},
     volume = {38},
     number = {1},
     doi = {10.1017/S0017089500031232},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500031232/}
}