[Kelley, Carl T.] N Carolina State Univ, Dept Math, Raleigh, NC 27695 USA.
[Qi, Liqun] Hong Kong Polytech Univ, Dept Appl Math, Kowloon, Hong Kong, Peoples R China.
[Tong, Xiaojiao] Hengyang Normal Univ, Dept Math & Computat Sci, Hengyang 421002, Peoples R China.
[Yin, Hongxia] Minnesota State Univ Mankato, Dept Math & Stat, Mankato, MN 56001 USA.
[Kelley, Carl T.] N Carolina State Univ, Dept Math, Box 8205, Raleigh, NC 27695 USA.