On the existence of a minimum of the integral $\int\sp {x\sb 1}\sb {x\sb 0}F(x,y,y')dx$ when $x\sb 0$ and $x\sb 1$ are conjugate points, and the geodesics on an ellipsoid of revolution: a revision of a theorem of Kneser's

W. F. Osgood
1901 Transactions of the American Mathematical Society  
doi:10.1090/s0002-9947-1901-1500563-0 fatcat:7nzsbcnsanf35gd5nbsam4d3tq