Perhaps you should try some spelling variations:
dung sai » dung tai, dung va, dung dat
tu sach » thu sach, te sach, tu cach
cua tre » cuu tre, cua triet, dua tren
va dung » van dung, va duong, vat dung
hieu le » hieu ve, hieu he, hieu ly
nang ma » tang ma, sang ma, nang cao
su sach » so sach, vu sach
ma hoi » mai hoi, xa hoi, ma hoa
le nam » ly nam, he nam, le na
thu va » thuc va, thue va, tu va
cua te » cua tu

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) OR (su sach)) ky nang ma hoi. hieu le nam thu va dung sai ((cua tre) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky nang ma hoi. hieu le nam thu va dung sai ((cua tre) OR (cua te))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (su sach)) ky nang ma hoi. hieu le nam thu va dung sai ((cua tre) or (cua te))*".