Perhaps you should try some spelling variations:
cau triet » cau trieu, su triet, cua triet
cau treo » cau theo, cau tren, cau trieu
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
nam luc » nang luc, nhan luc, nam thuc
mai hoi » mai khoi, dai hoi, lai hoi
y sang » _ sang, duy sang
luc va » duc va, tuc va, loc va
va dan » ca dan, va dao, va dau
dan va » doan va, dan ca, ban va

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 y sang ((mai hoi) or (xa hoi)). hieu van nam luc va dan va ((cau treo) OR (cau triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y sang ((mai hoi) OR (xa hoi)). hieu van nam luc va dan va ((cau treo) OR (cau triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y sang ((mai hoi) or (xa hoi)). hieu van nam luc va dan va ((cau treo) OR (cau triet))".
• Adding a wildcard symbol may retrieve word variants: tu sach y sang ((mai hoi) or (xa hoi)). hieu van nam luc va dan va ((cau treo) OR (cau triet))*.