Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
thanh ve » hanh ve, thanh va, thanh vien
va thanh » gia thanh, ban thanh, va tinh
cau luc » cau truc, cau phuc
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
cuu tre » cua tre, cau tren, cau treo
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
sai ky » sac ky
luc va » duc va, tuc va, loc va
ve cuu » ve cau, ve chu, ve cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc ((sach ky) or (sai ky)) nang ma hoi. ((hieu van) OR (hieu va)) cau luc va thanh ve cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc ((sach ky) OR (sai ky)) nang ma hoi. ((hieu van) OR (hieu va)) cau luc va thanh ve cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc ((sach ky) or (sai ky)) nang ma hoi. ((hieu van) OR (hieu va)) cau luc va thanh ve cuu tre".
• Adding a wildcard symbol may retrieve word variants: thuoc ((sach ky) or (sai ky)) nang ma hoi. ((hieu van) OR (hieu va)) cau luc va thanh ve cuu tre*.