TY - GEN A1 - An, Phan Thanh A1 - Phu, Hoang Xuan T1 - Outer $\gamma$-convexity in normed linear spaces T2 - Vietnam journal of mathematics Y1 - 1999 SN - 2305-2228 SN - 0866-7179 IS - 27 SP - 323 EP - 334 ER -