@article{TM_1955_46_a0,
     author = {M. M. Postnikov},
     title = {Investigations in homotopy theory of continuous mappings. {I.~The} algebraic theory of systems. {II.~The} natural system and homotopy type},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {3--158},
     publisher = {mathdoc},
     volume = {46},
     year = {1955},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_1955_46_a0/}
}