Perhaps you should try some spelling variations:
va hanh » van hanh, va thanh, va danh
cau loc » hau loc, cau hoc, cau luc
hieu va » lieu va, hieu qua
sach ky » sac ky, sach ty, sach kem
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu van
nang xa » nang x, lang xa, nang ma
loc va » hoc va, luc 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 ky) OR (sach y)) nang xa hoi. ((hieu ve) or (hieu va)) cau loc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach y)) nang xa hoi. ((hieu ve) OR (hieu va)) cau loc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) OR (sach y)) nang xa hoi. ((hieu ve) or (hieu va)) cau loc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) OR (sach y)) nang xa hoi. ((hieu ve) or (hieu va)) cau loc va hanh vi cua tre*.