Perhaps you should try some spelling variations:
cau tren » dau tren, ca tren, cau treo
sach thu » sach thue, sach thieu, sach tham
luc ngan » luc nganh, luc nhan, luat ngan
hieu van » hieu va, thien van, lieu va
cau luc » cau truc, cau phuc
hang vi » hang va, hanh vi, hang di
van cau » van dau, van hau, van chat
sach ty » sach y, sach tu, xach tay
xang xa » lang xa, mang xa, ang 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: tu ((sach ty) OR (sach thu)) xang xa hoi. hieu van cau luc ngan hang vi ((cau tren) or (cu tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach thu)) xang xa hoi. hieu van cau luc ngan hang vi ((cau tren) OR (cu tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) OR (sach thu)) xang xa hoi. hieu van cau luc ngan hang vi ((cau tren) or (cu tren))".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) OR (sach thu)) xang xa hoi. hieu van cau luc ngan hang vi ((cau tren) or (cu tren))*.