The geometry of the heat equation
Compositio Mathematica, Volume 12 (1954-1956), p. 147-156
@article{CM_1954-1956__12__147_0,
     author = {Ingraham, Richard L.},
     title = {The geometry of the heat equation},
     journal = {Compositio Mathematica},
     publisher = {Kraus Reprint},
     volume = {12},
     year = {1954-1956},
     pages = {147-156},
     zbl = {0057.32701},
     mrnumber = {68714},
     language = {en},
     url = {http://www.numdam.org/item/CM_1954-1956__12__147_0}
}
Ingraham, Richard L. The geometry of the heat equation. Compositio Mathematica, Volume 12 (1954-1956) pp. 147-156. http://www.numdam.org/item/CM_1954-1956__12__147_0/