@article{AL_1989_28_6_a1,
     author = {A. S. Denisov},
     title = {Homogeneous $O'$-elements in structural pre-orders},
     journal = {Algebra i logika},
     pages = {619--639},
     publisher = {mathdoc},
     volume = {28},
     number = {6},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1989_28_6_a1/}
}