Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
lam duoc » luat duoc, lam thuoc, tao duoc
nam duoc » nam thuoc, da duoc, dat duoc
sach tay » xach tay, sach hay, sach nay
chua tre » chua tri, cua tre, chua trieu
hieu van » hieu va, thien van, lieu va
tay lang » tai lang, tay tang, tay quang
lang xa » lang ha, dang xay, lang van
va hang » van hang, va lang, va hanh
va nang » van nang, da nang, cam nang
va chua » vua chua, ca chua, va chu

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 tay lang xa hoi. hieu van ((lam duoc) OR (nam duoc)) ((va hang) or (va nang)) va chua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach tay lang xa hoi. hieu van ((lam duoc) OR (nam duoc)) ((va hang) OR (va nang)) va chua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach tay lang xa hoi. hieu van ((lam duoc) OR (nam duoc)) ((va hang) or (va nang)) va chua tre".
• Adding a wildcard symbol may retrieve word variants: doc sach tay lang xa hoi. hieu van ((lam duoc) OR (nam duoc)) ((va hang) or (va nang)) va chua tre*.