@article{AL_1993_32_6_a5,
     author = {S. I. Mardaev},
     title = {Least fixed points in the {G\"odel-L\"ob} logic},
     journal = {Algebra i logika},
     pages = {683--689},
     publisher = {mathdoc},
     volume = {32},
     number = {6},
     year = {1993},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1993_32_6_a5/}
}