1. Ahsan, Z.: Indian J. Pure Appl. Maths. 31(2), 215–225 (2000)
2. Ahsan, Z., Bilal, M.: Int. J. Theo. Phys. 49, 2713–2722 (2010)
3. Ahsan, Z., Bilal, M.: J. Tensor Soc. 6(2), 127–134 (2012)
4. Ahsan, Z., Bilal, M.: Int. J. Theo. Phys. 52, 4275–4282 (2013)
5. Ahsan, Z., Ahsan, N., Ali, S.: Bull. Cal. Math. Soc. 93(5), 407–422 (2001)