Perhaps you should try some spelling variations:
hien khanh » hien hanh, hien nhanh, dien khanh
chieu xanh » chieu sach, chieu sang, chieu tinh
thong cong » trong cong, tong cong, thong thong
cong ban » cong bang, cong san, cong tan
ban than » ban thanh, van thanh, ban hang
than tap » toan tap, han tap, phan tap
san va » san van, ban va, han va
dan va » doan va, dan ca, ban va

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hien khanh) OR (chieu xanh)) - hanh ((san va) OR (dan va)) thong cong ban than tap~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hien khanh) or (chieu xanh)) - hanh ((san va) OR (dan va)) thong cong ban than tap~".
• Adding a wildcard symbol may retrieve word variants: hoc ((hien khanh) or (chieu xanh)) - hanh ((san va) OR (dan va)) thong cong ban than tap*.