1. Alizadeh, H., Rezapour, S. H. and Vaezpour, S. M., On ɛ-simultaneous Approximation in Quotient Spaces, The Australian Journal of Mathematical Analysis and Applications, 5:2(2009) 1–7.
2. Goel, D. S., Holland, A. S., Nasim, C. and Shaney, B. N., On Best Simultaneous Approximation in Normed Linear Spaces, Canad. Math. Bull., 17:4(1974), 523–527.
3. Holland, A. S., Shaney, B. N. and Tzimbalaeio, J., On Best Simultaneous Approximation, J. Approx. Theory, 17 (1976), 187–188.
4. Iranmanesh, M. and Mohebi, H., On Best Simultaneous Approximation in Quotient Spaces, Analysis in Theory and Applications, 23:1(2007), 35–49.
5. Iranmanesh, M. and Mohebi, H., Best Simultaneous Approximation in Tensor Product Spaces, Applied Mathematics Sciences, 1:18(2007), 883–894.