Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
cau tren » cu tren, dau tren, ca tren
cam quoc » cac quoc, cao quoc, nam quoc
dang van » hoang van, hang va
cuu tre » cua tre, cau treo
sach ty » sach y, sach tu, sach thu
tu sach » thu sach, su sach, te sach
tang ma » mang may, tang van
hieu va » lieu va, hieu qua
va cam » va cham, va cac, va cao
gia » giao

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 ty ((tang ma) or (dang van)) hoi. hieu va cam quoc gia thanh tai ((cuu tre) OR (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((tang ma) OR (dang van)) hoi. hieu va cam quoc gia thanh tai ((cuu tre) OR (cau tren))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((tang ma) or (dang van)) hoi. hieu va cam quoc gia thanh tai ((cuu tre) OR (cau tren))*".