@article{AL_1981_20_4_a3,
     author = {A. A. Nikitin},
     title = {Homomorphisms of freely generated projective planes},
     journal = {Algebra i logika},
     pages = {419--426},
     publisher = {mathdoc},
     volume = {20},
     number = {4},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1981_20_4_a3/}
}