Perhaps you should try some spelling variations:
danh dien » dinh dien, danh kien, danh lien
hac thuc » hoc thuc, ha thuc, thach thuc
cau tren » dau tren, ca tren, cau treo
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
cu tren » tu tren, dua tren

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 dien ((cau tren) OR (cu tren))~.
• 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 dien ((cau tren) OR (cu tren)).
• 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 dien ((cau tren) OR (cu tren))".
• Adding a wildcard symbol may retrieve word variants: so sach y ((nang xa) or (nang ma)) hoi. hieu van hac thuc va danh dien ((cau tren) OR (cu tren))*.