[1] Natl Inst Technol, Dept Math, Warangal 506004, Telangana, India
[2] Govt Coll, Dept Math, Jaitwara 485221, MP, India
[3] Ton Duc Thang Univ, Informetr Res Grp, Ho Chi Minh City 758307, Vietnam
[4] Ton Duc Thang Univ, Fac Business Adm, Ho Chi Minh City 758307, Vietnam
[5] Univ Molise, Dept Econ, Via Sanctis, I-86100 Campobasso, Italy
[6] Lithuanian Inst Agr Econ, A Vivulskio G 4A-13, LT-03220 Vilnius, Lithuania
[7] Tsinghua Univ, Sch Econ & Management, Beijing 100084, Peoples R China