Perhaps you should try some spelling variations:
dua tren » dung tren
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
ty tang » tay tang, ty xang, ty hang
tang xa » trang xa, tang ma, lang xa
hieu va » lieu va, hieu qua
cuu tre » cua tre, cau tren, cau treo
va cam » va cham, va cac, va cao
luc va » tuc va, loc 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 ty tang xa hoi. hieu va cam ((luc va) OR (duc va)) hanh vi ((cuu tre) or (dua tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty tang xa hoi. hieu va cam ((luc va) OR (duc va)) hanh vi ((cuu tre) OR (dua tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty tang xa hoi. hieu va cam ((luc va) OR (duc va)) hanh vi ((cuu tre) or (dua tren))".
• Adding a wildcard symbol may retrieve word variants: tu sach ty tang xa hoi. hieu va cam ((luc va) OR (duc va)) hanh vi ((cuu tre) or (dua tren))*.