Perhaps you should try some spelling variations:
hien xanh » hien hanh, hien nhanh, chieu xanh
trinh van » trinh han, trinh quan, trinh toan
dung cong » dung trong
trang va » tran van, hang va
trinh va » trinh vat, trinh ve, trinh vi
cong dan » cong san, cong tan, huong dan
dan than » dan chan, ban than, van than
than tu » thanh tu, thang tu, phan tu

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 va) OR (((trinh va) OR (trinh van)))) dung cong dan than tu~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hien xanh - hanh ((trang va) or (((trinh va) OR (trinh van)))) dung cong dan than tu~".
• Adding a wildcard symbol may retrieve word variants: hoc hien xanh - hanh ((trang va) or (((trinh va) OR (trinh van)))) dung cong dan than tu*.