Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
lam duoc » nam duoc, luat duoc, lam thuoc
ty lang » tay lang, ty hang, tu lang
hieu va » lieu va, hieu qua
duoc va » nuoc va, duc va, duoc ma
va lang » va nang, hoa lang
lang va » lang van, hang va, lang ha
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
va lam » van lam, va lap

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