Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
sach thu » sach thue, sach thieu, sach tham
cham hoc » cham soc, chat hoc, cham hoi
hieu va » lieu va, hieu qua
hoc van » hoc dan, hoc va, hoc vat
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, xach tay
hieu vu » hieu ve, hieu su, dieu vu
xang xa » lang xa, mang xa, ang xa
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 ty) OR (sach thu)) xang xa hoi. ((hieu vu) or (hieu va)) cham hoc van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach thu)) xang xa hoi. ((hieu vu) OR (hieu va)) cham hoc van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) OR (sach thu)) xang xa hoi. ((hieu vu) or (hieu va)) cham hoc van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) OR (sach thu)) xang xa hoi. ((hieu vu) or (hieu va)) cham hoc van hanh vi cua tre*.