Gauss, Carl Friedrich (1877). "Theoria attractionis corporum sphaeroidicorum ellipticorum homogeneorum methodo nova tractata" [The theory of the attraction of homogeneous spheroidal elliptic bodies treated by a new method]. In Schering, Ernst Christian Julius; Brendel, Martin (eds.). Carl Friedrich Gauss Werke [Works of Carl Friedrich Gauss] (in Latin and German). Vol. 5 (2nd ed.). Gedruckt in der Dieterichschen Universitätsdruckerei (W.F. Kaestner). pp. 2–22. Gauss mentions Newton's Principiaproposition XCI regarding finding the force exerted by a sphere on a point anywhere along an axis passing through the sphere.
Gauss, Carl Friedrich (1877). "Theoria attractionis corporum sphaeroidicorum ellipticorum homogeneorum methodo nova tractata" [The theory of the attraction of homogeneous spheroidal elliptic bodies treated by a new method]. In Schering, Ernst Christian Julius; Brendel, Martin (eds.). Carl Friedrich Gauss Werke [Works of Carl Friedrich Gauss] (in Latin and German). Vol. 5 (2nd ed.). Gedruckt in der Dieterichschen Universitätsdruckerei (W.F. Kaestner). pp. 2–22. Gauss mentions Newton's Principiaproposition XCI regarding finding the force exerted by a sphere on a point anywhere along an axis passing through the sphere.