Calculation of the Stability Index in Parameter-Dependent Calculus of Variations Problems: Buckling of a Twisted Elastic Strut. - Kathleen A. Hoffman; Robert S. Manning; Randy C. Paffenroth (SIAM J. Appl. Dyn. Syst., 2002)

An Extended Conjugate Point Theory with Application to the Stability of Planar Buckling of an Elastic Rod Subject to a Repulsive Self-Potential. - Kathleen A. Hoffman; Robert S. Manning (SIAM J. Math. Anal., 2009)

Conjugate Points Revisited and Neumann-Neumann Problems. - Robert S. Manning (SIAM Rev., 2009)