Equivalence of second order optimality conditions for bang-bang control problems. Part 1: Main results N.P. Osmolovskii, H. Maurer (2005) Control and Cybernetics
Equivalence of second order optimality conditions for bang-bang control problems. Part 2: Proofs, variational derivatives and representations N. Osmolovskii, H. Maurer (2007) Control and Cybernetics
Error analysis of discrete approximations to bang-bang optimal control problems: the linear case Vladimir Veliov (2005) Control and Cybernetics