Perhaps you should try some spelling variations:
thanh lap » thanh san, phan lap, thanh hai
sach thu » sach thue, sach thieu, sach tham
sach ty » sach y, sach tu, xach tay
nang ma » tang ma, sang ma, nang cao
hieu vu » hieu va, hieu ve, hieu su
vu pham » su pham, vi pham, vu kham
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ty) OR (sach thu)) nang ma hoi. hieu vu pham duc va ((dinh van) or (thanh lap)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach thu)) nang ma hoi. hieu vu pham duc va ((dinh van) OR (thanh lap)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) OR (sach thu)) nang ma hoi. hieu vu pham duc va ((dinh van) or (thanh lap)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) OR (sach thu)) nang ma hoi. hieu vu pham duc va ((dinh van) or (thanh lap)) cua tre*.