1. On certain transformations not changing the integral curves of a differential equation of the first order;Adamov;Mat. Sb.,1948
2. Behavior of solutions of second order selfadjoint differential equations;Barrett,1955
3. Disconjugacy of 2nd order linear differential equations with nonnegative coefficients;Barrett,1959
4. The theorems of oscillation of Sturm and Klein, I & II;Bôcher;Bull. Am. Math. Soc.,1897
5. The theorems of oscillation of Sturm and Klein, I & II;Bôcher;Bull. Am. Math. Soc.,1897