1. Bandyopadhyay, P., Li, Y., Bor-Luh, L., et al.: Proximinality in Banach spaces. J. Math. Anal. Appl., 341, 309–317 (2008)
2. Bandyopadhyay, P., Bor-Luh, L., Rao, T.S.S.R.K.: Ball proximinality in Banach spaces. Banach Spaces and Their Applications in Analysis, Walter de Gruyter, Berlin, 2007
3. Bessaga, C., Pelczynski, A.: On bases and unconditional convergence of series in Banach spaces. Studia Math., 17, 151–164 (1958)
4. Cheney, E. W., Wulbert, D. E.: Corrigendum: “The existence and unicity of best approximations”. Math. Scand., 27, 245 (1970)(1971)
5. Cheng, L., Cheng, Q., Luo, Z.: On some new characterizations of weakly compact sets in Banach spaces. Studia Math., 201, 155–166 (2010)