Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
hanh le » thanh le, hanh ve, hanh de
va hanh » van hanh, va thanh, va danh
cac dac » cac dan, cac dai, cac bac
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac nuoc
va lang » va nang, hoa lang
v lang » o lang, _ lang, van lang
le cua » ly cua
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: thuoc sach ((v lang) OR (va lang)) xa hoi. hieu va ((cac duc) or (cac dac)) va hanh le cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach ((v lang) OR (va lang)) xa hoi. hieu va ((cac duc) OR (cac dac)) va hanh le cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc sach ((v lang) OR (va lang)) xa hoi. hieu va ((cac duc) or (cac dac)) va hanh le cua te".
• Adding a wildcard symbol may retrieve word variants: thuoc sach ((v lang) OR (va lang)) xa hoi. hieu va ((cac duc) or (cac dac)) va hanh le cua te*.