Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
hieu va » hieu qua
cam luc » cam xuc, cau luc
va danh » va dinh, va dan, va hanh
danh vi » hanh vi, dinh vi, danh di
cua tre » cua te, cuu tre, cua triet
y lang » o lang, tay lang, yen lang
_ lang » o lang, _ land
luc va » duc va, tuc va, loc va
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((y lang) OR (_ lang)) xa hoi. ((lieu va) or (hieu va)) cam luc va danh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((y lang) OR (_ lang)) xa hoi. ((lieu va) OR (hieu va)) cam luc va danh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((y lang) OR (_ lang)) xa hoi. ((lieu va) or (hieu va)) cam luc va danh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((y lang) OR (_ lang)) xa hoi. ((lieu va) or (hieu va)) cam luc va danh vi cua tre*.