Isometric deformation of timelike surfaces with parallel mean curvature direction in L4(L4中平均曲率方向平行的类时曲面的等距变形) von ZHANGYuan-zheng(张远征)

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Hopf-type theorem for 2-type topolgical two spheres in S7(S7中2型拓扑球面的Hopf型定理) von ZHANGYuan-zheng(张远征)

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