Perhaps you should try some spelling variations:
thanh vi » thanh va, thanh ve, nhanh vi
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, su sach, te sach
xang xa » lang xa, mang xa, ang xa
hieu va » lieu va, hieu qua
y xang » ty xang
va cau » van cau, va cac, va dau
tuc va » thuc va, truc va, duc 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 xang xa hoi. hieu va cau ((tuc va) OR (tuc xa)) ((thanh vi) or (hanh vi)) cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y xang xa hoi. hieu va cau ((tuc va) OR (tuc xa)) ((thanh vi) OR (hanh vi)) cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y xang xa hoi. hieu va cau ((tuc va) OR (tuc xa)) ((thanh vi) or (hanh vi)) cau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach y xang xa hoi. hieu va cau ((tuc va) OR (tuc xa)) ((thanh vi) or (hanh vi)) cau tren*.