Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
thanh vi » thanh va, thanh ve, nhanh vi
cau tren » cu tren, dau tren, ca tren
hieu va » lieu va, hieu qua
xang xa » lang xa, mang xa, ang xa
va cau » van cau, va cac, va dau
luc va » duc va, loc va
y xang » ty xang
tuc va » thuc va, truc va, tuc xa

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc sach y xang xa hoi. hieu va cau ((luc va) OR (tuc va)) ((thanh vi) or (hanh vi)) cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach y xang xa hoi. hieu va cau ((luc va) OR (tuc va)) ((thanh vi) OR (hanh vi)) cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc sach y xang xa hoi. hieu va cau ((luc va) OR (tuc va)) ((thanh vi) or (hanh vi)) cau tren".
• Adding a wildcard symbol may retrieve word variants: thuoc sach y xang xa hoi. hieu va cau ((luc va) OR (tuc va)) ((thanh vi) or (hanh vi)) cau tren*.