Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
duc van » duc va, duc tan, duc manh
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
ca duc » cao duc, cua duc, ca dua
anh vi » hanh vi, anh va, anh vu
anh ve » hanh ve, anh va, anh viet
qua ca » qua cac, qua cua, qua cai

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 (nang ma)) hoi. hieu qua ca duc van ((anh vi) or (anh ve)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (nang ma)) hoi. hieu qua ca duc van ((anh vi) OR (anh ve)) cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) or (nang ma)) hoi. hieu qua ca duc van ((anh vi) or (anh ve)) cua tre*.