@misc{RM_1988_43_6_a4,
     title = {Letters {of~A.\,N.~Kolmogorov} {to~A.~Heyting}},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {89--93},
     publisher = {mathdoc},
     volume = {43},
     number = {6},
     year = {1988},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_1988_43_6_a4/}
}