Eigenvalue and eigenfunction computations for Sturm-Liouville problems. - Paul B. Bailey; Anton Zettl (ACM Trans. Math. Softw., 1991)

Algorithm 700: A Fortran software package for Sturm-Liouville problems. - Paul B. Bailey; Anton Zettl (ACM Trans. Math. Softw., 1991)

Algorithm 810: The SLEIGN2 Sturm-Liouville Code. - Paul B. Bailey; W. Norrie Everitt; Anton Zettl (ACM Trans. Math. Softw., 2001)

Finite spectrum of 2nth order boundary value problems. - Ji-jun Ao; Jiong Sun 002; Anton Zettl (Appl. Math. Lett., 2015)