Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
va thanh » gia thanh, ban thanh, va tinh
tu sach » thu sach, te sach, tu cach
tai cua » thai cua, tai cuc, tri cua
hieu ve » hieu va, hieu van
hieu vu » hieu va, hieu su, dieu vu
cua tre » cua te, cuu tre, cua triet
su sach » so sach, vu sach
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
cam lo » nam lo, cam ly, cam o
y nang » ky nang, ly nang, v nang
lo va » lo van, lao va, ly va

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)) y nang ma hoi. ((hieu vu) OR (hieu ve)) cam lo va thanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) y nang ma hoi. ((hieu vu) OR (hieu ve)) cam lo va thanh tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) y nang ma hoi. ((hieu vu) OR (hieu ve)) cam lo va thanh tai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) y nang ma hoi. ((hieu vu) OR (hieu ve)) cam lo va thanh tai cua tre*.