Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
hang tai » hang va, dung tai
hieu van » thien van, lieu va, hieu ve
nam tuc » nam thuc, nam truc, nam tu
dang xa » dang xay, lang xa, dang va
tai cua » thai cua, tai cuc, tri cua
dang ha » dong ha, dung ha, lang ha
va hang » van hang, va nang, va lang
hieu va » lieu va, hieu qua
tuc va » thuc va, truc va, tuc xa
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach y ((dang xa) or (dang ha)) hoi. ((hieu van) OR (hieu va)) nam tuc va hang tai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach y ((dang xa) OR (dang ha)) hoi. ((hieu van) OR (hieu va)) nam tuc va hang tai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach y ((dang xa) or (dang ha)) hoi. ((hieu van) OR (hieu va)) nam tuc va hang tai cua te".
• Adding a wildcard symbol may retrieve word variants: doc sach y ((dang xa) or (dang ha)) hoi. ((hieu van) OR (hieu va)) nam tuc va hang tai cua te*.