Perhaps you should try some spelling variations:
hieu hieu » hien hieu, hieu hien, thien hieu
hieu cac » hieu luc, hieu va, hieu van
danh vai » danh sai, doanh van, dang van
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
danh va » doanh va, hanh va, anh va
cua tre » cua te, cuu tre, cua triet
do va » do van, so va
bo va » bao va, so va, co va
x hoi » xa hoi, o hoi, x ho

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 ky nang x hoi. hieu hieu cac ((bo va) or (do va)) ((danh vai) OR (danh va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. hieu hieu cac ((bo va) OR (do va)) ((danh vai) OR (danh va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. hieu hieu cac ((bo va) or (do va)) ((danh vai) OR (danh va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. hieu hieu cac ((bo va) or (do va)) ((danh vai) OR (danh va)) cua tre*.