This was similar to the results published by Nguyen Ngoc Sang (2014), Nguyen Van Sang (2013), Ravi Elhence (1994) and Gulati (2010).
Nhận xét của chúng tôi tương tự Nguyễn Ngọc Sáng (2014), Nguyễn Văn Sang (2013), Ravi Elhence (1994), Gulati (2010).