Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
sach tu » sach thu, cach tu, sach ty
dinh vi » dinh ve, dinh viet, dinh tri
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
tu nang » tru nang, tu nong, tu nano
ve cac » va cac, vien cac
ve cam » ve cham, va cam, ve cai
xuc va » duc va, tuc va, luc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach tu nang ma hoa. hieu ((ve cam) OR (ve cac)) xuc va ((dinh vi) or (chinh tri)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach tu nang ma hoa. hieu ((ve cam) OR (ve cac)) xuc va ((dinh vi) OR (chinh tri)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach tu nang ma hoa. hieu ((ve cam) OR (ve cac)) xuc va ((dinh vi) or (chinh tri)) cua tre".
• Adding a wildcard symbol may retrieve word variants: hoc sach tu nang ma hoa. hieu ((ve cam) OR (ve cac)) xuc va ((dinh vi) or (chinh tri)) cua tre*.