共 12 条
[1]
Bellman RKL, 1963, DIFFERENTIAL DIFFERE, DOI 10.1063/1.3050672
[3]
Levin J.J., 1963, P AM MATH SOC, V14, P435, DOI [10.2307/2034270, https://doi.org/10.1090/S0002-9939-1963-0152852-8, DOI 10.1090/S0002-9939-1963-0152852-8]
[8]
Levinson N., 1960, J MATH ANAL APPL, V1, P1