Perhaps you should try some spelling variations:
hac thuc » hoc thuc, ha thuc, thach thuc
cua tre » cua te, cua triet, dua tren
thuc va » thuc vat, thuc dan, thuc day
so sach » so sanh, bo sach, co sach
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
cuu tre » cau tren, cau treo
va hac » van hac, va khac, va cac
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va

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