Perhaps you should try some spelling variations:
hien xanh » hien hanh, hien nhanh, chieu xanh
trang xay » trong xay, trang va, trinh xay
dung cong » dung trong
trang xa » trang va, trang ha, trong xa
cong ban » cong bang, cong san, cong tan
toan cau » toan cao, toan ban, toan tap
phan dau » phan tu, hang dau

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 xanh - hanh ((trang xay) OR (trang xa)) dung cong ban ((toan cau) OR (phan dau))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hien xanh - hanh ((trang xay) OR (trang xa)) dung cong ban ((toan cau) or (phan dau))~".
• Adding a wildcard symbol may retrieve word variants: hoc hien xanh - hanh ((trang xay) OR (trang xa)) dung cong ban ((toan cau) or (phan dau))*.