1. Boundary Layer Problems Exhibiting Resonance;Ackerberg;Studies in Appl. Math.,1970
2. Subfunctions for Ordinary Differential Equations II;Akô;Funkcialaj Eqvacioj,1967
3. On the Equations of the Calculus of Variations (in French);Bernshtein;Ann. Ec. Sup. Norm.,1912
4. The Two-Point Problem for a Class of Ordinary Differential Equations with a Small Parameter Coefficient of the Derivative;Boglaev;USSR Comp. Math. Math. Phys.,1970