@article{SF_1986__34_134834,
     author = {L. Pol\'ak and J. Kadourek},
     title = {On the word problem for free completely regular semigroups.},
     journal = {Semigroup forum},
     pages = {127--138},
     publisher = {mathdoc},
     volume = {34},
     year = {1986},
     zbl = {0607.20031},
     url = {http://geodesic.mathdoc.fr/item/SF_1986__34_134834/}
}