R. V. Gamkrelidze, G. L. Haratišvili, The theory of the first variation in extremal problems

Title: The theory of the first variation in extremal problems
Authors: R. V. Gamkrelidze, G. L. Haratišvili
Journal title: Sakharth. SSR Mecn. Akad. Moambe
Year: 1967
Volume: 46
Pages: 27–31