Perhaps you should try some spelling variations:
dan thanh » dang thanh, danh thanh, ban thanh
cuu thuc » cuu tac
thanh tu » hanh tu, nhanh tu, thanh tung
hieu van » thien van, lieu va, hieu ve
thuc dan » thuc hanh, hoc dan, thuc vat
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
tu cua » hu cua, vu cua
cua te » cua tu

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