Zorii, N. V. “Necessary and Sufficient Conditions for the Solvability of the Gauss Variational Problem”.
Ukrains’kyi Matematychnyi Zhurnal
, vol. 57, no. 1, Jan. 2005, pp. 60–83,
https://umj.imath.kiev.ua/index.php/umj/article/view/3574
.