@article{CM_1968__20__3_0,
     author = {Troelstra, A. S.},
     title = {The scientific work of {A.} {Heyting}},
     journal = {Compositio Mathematica},
     pages = {3--12},
     publisher = {Wolters-Noordhoff Publishing},
     volume = {20},
     year = {1968},
     mrnumber = {224427},
     zbl = {0155.00909},
     language = {en},
     url = {http://www.numdam.org/item/CM_1968__20__3_0/}
}