Perhaps you should try some spelling variations:
dieu cua » dieu tra
vat hanh » vat thanh, van hanh, va hanh
sach thu » sach thue, sach thieu, sach tham
cham hoi » cham voi, cham h'roi, pham hoai
hieu va » lieu va, hieu qua
hoi vat » hoi va, hoc vat, hoi dat
sach ty » sach y, sach tu, xach tay
xang xa » lang xa, mang xa, ang xa
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 ty) or (sach thu)) xang xa hoi. ((dieu cua) or (hieu va)) cham hoi vat 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. ((dieu cua) OR (hieu va)) cham hoi vat hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) or (sach thu)) xang xa hoi. ((dieu cua) or (hieu va)) cham hoi vat hanh vi cua tre*.