Robuta

https://thescipub.com/abstract/jmssp.2009.107.111 A Rigorous Proof for the Invariant Study of the Problem in Section VI in "Matched Subspace... rigorous proof for the invariant study problem https://ems.press/journals/zaa/articles/11330 A Numerically Rigorous Proof of Curve Veering in an Eigenvalue Problem for Differential Equations |... rigorous proof differential equations curve veering problem