Perhaps you should try some spelling variations:
dang mai » dang hai, dang mau, dang bai
te sach » toc sach
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
cuu tre » cua tre, cau tren, cau treo
hieu ve » hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ky dang » ky nang, ky danh
tro ca » tro cua, tro cap, tho ca
dao vi » dao voi, dao va, dao li
dao ve » bao ve, dap ve, dau ve

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky dang mai hoi. ((hieu ve) or (hieu va)) cac tro ca ((dao vi) OR (dao ve)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky dang mai hoi. ((hieu ve) OR (hieu va)) cac tro ca ((dao vi) OR (dao ve)) cuu tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky dang mai hoi. ((hieu ve) or (hieu va)) cac tro ca ((dao vi) OR (dao ve)) cuu tre*".