Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thanh vi » thanh va, thanh ve, nhanh vi
dua tren » dung tren
xang xa » lang xa, mang xa, ang xa
hieu va » lieu va, hieu qua
cam duc » cam xuc, cao duc, pham duc
cu tren » tu tren
y xang » ty xang
va cam » va cham, va cac, va cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach y xang xa hoi. hieu va cam duc va ((thanh vi) or (hanh vi)) ((cu tren) or (dua tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y xang xa hoi. hieu va cam duc va ((thanh vi) OR (hanh vi)) ((cu tren) OR (dua tren)).
• Adding a wildcard symbol may retrieve word variants: toc sach y xang xa hoi. hieu va cam duc va ((thanh vi) or (hanh vi)) ((cu tren) or (dua tren))*.