Perhaps you should try some spelling variations:
kinh tri » dinh tri, minh tri, tinh tri
tu sach » thu sach, su sach, te sach
sach tu » sach thu, cach tu, sach ty
tu nano » truc nano
nano xa » nano va, nano bac, nano cau
hieu ve » hieu van
hieu va » lieu va, hieu qua
cua su » qua su

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach tu nano xa hoi. ((hieu ve) OR (hieu va)) cam ((tuc xa) OR (duc va)) kinh tri cua su~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach tu nano xa hoi. ((hieu ve) OR (hieu va)) cam ((tuc xa) or (duc va)) kinh tri cua su~".
• Adding a wildcard symbol may retrieve word variants: tu sach tu nano xa hoi. ((hieu ve) OR (hieu va)) cam ((tuc xa) or (duc va)) kinh tri cua su*.