Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
dan thai » dang thai, dan thi, dan than
cau nuoc » cap nuoc, cac nuoc, dau nuoc
hieu van » hieu va, thien van, lieu va
cuu tre » cua tre, cau treo
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
van cau » van dau, van hau, van chat
va dan » ca dan, va dao, va dau

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 y ((nang xa) or (nang ma)) hoi. hieu van cau nuoc va dan thai ((cuu tre) OR (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((nang xa) OR (nang ma)) hoi. hieu van cau nuoc va dan thai ((cuu tre) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((nang xa) or (nang ma)) hoi. hieu van cau nuoc va dan thai ((cuu tre) OR (cau tren))".
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang xa) or (nang ma)) hoi. hieu van cau nuoc va dan thai ((cuu tre) OR (cau tren))*.