Perhaps you should try some spelling variations:
hac thuc » hoc thuc, ha thuc, thach thuc
hieu van » hieu va, thien van, lieu va
so sach » so sanh, bo sach, co sach
va danh » va dinh, va dan, va hanh
thuc va » thuc vat, thuc dan, thuc day
van hac » van hoc, van ha, van hai
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
di cuu » di cau, dinh cuu
di cua » dai cua, doi cua, de 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 y ((nang xa) or (nang ma)) hoi. hieu van hac thuc va danh ((di cuu) OR (di cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y ((nang xa) OR (nang ma)) hoi. hieu van hac thuc va danh ((di cuu) OR (di cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach y ((nang xa) or (nang ma)) hoi. hieu van hac thuc va danh ((di cuu) OR (di cua)) tre".
• Adding a wildcard symbol may retrieve word variants: so sach y ((nang xa) or (nang ma)) hoi. hieu van hac thuc va danh ((di cuu) OR (di cua)) tre*.