Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
ban hanh » ban hang
hieu van » hieu va, thien van, lieu va
cua tre » cua te, cuu tre, cua triet
duc ban » duc tan, duc van, dua ban
cau duc » cao duc, cau luc, chu duc
su sach » so sach
lang xa » lang ha, dang xay, lang van
tu lang » cu lang, tu lanh, xu lang
vu sach » vu bach, vu khach
van cau » van dau, van hau, van chat

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) OR (vu sach)) tu lang xa hoi. hieu van cau duc ban hanh vi ((cua tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) tu lang xa hoi. hieu van cau duc ban hanh vi ((cua tre) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) OR (vu sach)) tu lang xa hoi. hieu van cau duc ban hanh vi ((cua tre) or (cau tren))".
• Adding a wildcard symbol may retrieve word variants: ((su sach) OR (vu sach)) tu lang xa hoi. hieu van cau duc ban hanh vi ((cua tre) or (cau tren))*.