Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dua tren » dung tren
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
cac luc » cau luc, coc luc, cac nuoc
va hang » van hang, va nang, va lang
hang di » hang doi, hang vi, hang dien
cu tren » tu tren
luc va » duc 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: toc sach _ lang xa hoi. hieu va cac luc va hang di ((dua tren) or (cu tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach _ lang xa hoi. hieu va cac luc va hang di ((dua tren) OR (cu tren)).
• Adding a wildcard symbol may retrieve word variants: toc sach _ lang xa hoi. hieu va cac luc va hang di ((dua tren) or (cu tren))*.