Perhaps you should try some spelling variations:
hien hieu » thien hieu, nhien lieu, dien chieu
hieu hoc » lieu hoc, hieu hoa, tieu hoc
danh vai » danh sai, doanh van, dang van
nang xa » nang x, lang xa, nang ma
danh va » doanh va, hanh va, anh va
cua tre » cua te, cuu tre, cua triet
sach v » sach va, sach 2, sach vay
nuoc » quoc, duoc, ngoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach v) OR (sach y)) nang xa hoi. hien hieu hoc nuoc va ((danh vai) or (danh va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach v) OR (sach y)) nang xa hoi. hien hieu hoc nuoc va ((danh vai) OR (danh va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach v) OR (sach y)) nang xa hoi. hien hieu hoc nuoc va ((danh vai) or (danh va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach v) OR (sach y)) nang xa hoi. hien hieu hoc nuoc va ((danh vai) or (danh va)) cua tre*.