@article{MT_1992_21_a4,
     author = {V. K. Ionin},
     title = {On the definition of physical structures},
     journal = {Matemati\v{c}eskie trudy},
     pages = {42--51},
     publisher = {mathdoc},
     volume = {21},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MT_1992_21_a4/}
}