Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh doi » thanh doi, hanh noi, hang doi
hieu va » lieu va, hieu qua
cao loc » cao hoc, cao toc, cao oc
va hanh » van hanh, va thanh, va danh
doi cua » dai cua, hoi cua, dong cua
cua tre » cua te, cuu tre, cua triet
v lang » va lang, _ lang, van lang
o lang » hoa lang, hoi lang
va cao » va cac, va co, va dao
loc va » hoc va, luc 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 ((v lang) or (o lang)) xa hoi. hieu va cao loc va hanh doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((v lang) OR (o lang)) xa hoi. hieu va cao loc va hanh doi cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach ((v lang) or (o lang)) xa hoi. hieu va cao loc va hanh doi cua tre*.