@article{SF_1974__9_134073,
     author = {M.S. Putcha},
     title = {Viewing results on ...-indecomposable semigroups as solutions to mathematical puzzles.},
     journal = {Semigroup forum},
     pages = {181--183},
     publisher = {mathdoc},
     volume = {9},
     year = {1974},
     zbl = {0292.20059},
     url = {http://geodesic.mathdoc.fr/item/SF_1974__9_134073/}
}