Perhaps you should try some spelling variations:
hieu cua » hieu qua, dieu cua, bieu cua
thanh ve » hanh ve, thanh va, thanh vien
va thanh » gia thanh, ban thanh, va tinh
cac tac » cac toc, cac bac, cac dac
sach ky » sac ky, sach ty, sach kem
cac tuc » cac toc, cac tu, cac nuoc
cuu tre » cua tre, cau tren, cau treo
tang xa » trang xa, tang ma, lang xa
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: so ((sach ky) OR (sach y)) tang xa hoi. hieu cua ((cac tuc) or (cac tac)) va thanh ve cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((sach ky) OR (sach y)) tang xa hoi. hieu cua ((cac tuc) OR (cac tac)) va thanh ve cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so ((sach ky) OR (sach y)) tang xa hoi. hieu cua ((cac tuc) or (cac tac)) va thanh ve cuu tre".
• Adding a wildcard symbol may retrieve word variants: so ((sach ky) OR (sach y)) tang xa hoi. hieu cua ((cac tuc) or (cac tac)) va thanh ve cuu tre*.