Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
va hanh » van hanh, va thanh, va danh
cham tu » pham tu, cam tu, chai tu
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
hieu ve » hieu van
nang xa » nang x, lang xa, nang ma
lang ha » long ha
cua tre » cua te, cuu tre, cua triet
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 ky ((nang xa) or (lang ha)) hoi. ((hieu ve) OR (hieu va)) cham tu va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (lang ha)) hoi. ((hieu ve) OR (hieu va)) cham tu va hanh vi cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang xa) or (lang ha)) hoi. ((hieu ve) OR (hieu va)) cham tu va hanh vi cua tre*".