Perhaps you should try some spelling variations:
sach truc » cach thuc, sach tren, sach thu
hieu van » hieu va, thien van, lieu va
danh va » doanh va, hanh va, anh va
va danh » va dinh, va dan, va hanh
cao duc » dao duc, cao suc, giao duc
van cao » van dao, van bao, van hao
tu sach » thu sach, su sach, te sach
nang xa » lang xa, nang ma, mang xa
cua tu » cua tuc, cua su, cua cu

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