1. J. Dieudonné, Acta. Sci. Math. Szeged,12, Pars B, 38?40 (1950).
2. J. A. Yorke, Funkcialaj Ekvacioj,13, 19?21 (1970).
3. A. N. Godunov, "Counterexample of Peano's theorem in an infinite-dimensional Hilbert space," Vestnik MGU, Seriya Matem. i Mekhan., No. 5, 31?34 (1972).
4. A. Cellina, Bull. Amer. Math. Soc.,78, No. 6, 1069?1072 (1972).
5. M. M. Day, Proc. Am. Math. Soc.,13, 655?658 (1962).