[1] Normal Univ, Coll Math, Dianxi Sci & Technol, Lincang 677000, Peoples R China
[2] Fasa Univ, Fac Sci, Dept Stat, Fasa 7461686131, Iran
[3] Cankaya Univ Balgat, Fac Art & Sci, Dept Math, TR-06530 Ankara, Turkey
[4] Shiraz Univ, Fac Sci, Dept Stat, Shiraz 7194685115, Iran