1. Disconjugacy;Coppel,1971
2. Non-oscillation of solutions of the equations x(n)+p1(t)x(n−1)+⋯+pn(t)x=0;Levin;Soviet Math. Surveys,1969
3. Spaces of linear ordinary differential equations and flag varieties;Shapiro;Izvesti Akad. Nauk USSR,1990
4. Oscillation criteria for second-order linear differential equations;Nehari;Trans. Amer. Math. Soc.,1957
5. Disconjugacy of second-order linear differential equations with non-negative coefficients;Barrett;Proc. Amer. Math. Soc.,1959