Switchings of optimal controls and the equation y ( 4 ) + | y | α s i g n y = 0 , 0 < α < 1 Pavol Brunovský; John J. Mallet-Paret — 1985 Časopis pro pěstování matematiky
Almost Floquet and generalized almost Floquet systems Herbert I. Freedman; John J. Mallet-Paret — 1976 Czechoslovak Mathematical Journal