Perhaps you should try some spelling variations:
quoc ban » quoc bao, quoc lan, quoc quan
sach ty » sach y, sach tu, sach thu
xuc ban » duc ban, cuc ban, xuat ban
qua cam » qua cham, qua cac, qua ca
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
cua tre » cua te, cuu tre, cua triet
anh vi » hanh vi, anh va, anh ve
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 ((nang xa) or (nang ma)) hoi. hieu qua cam ((xuc ban) OR (quoc ban)) anh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang xa) OR (nang ma)) hoi. hieu qua cam ((xuc ban) OR (quoc ban)) anh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((nang xa) or (nang ma)) hoi. hieu qua cam ((xuc ban) OR (quoc ban)) anh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang xa) or (nang ma)) hoi. hieu qua cam ((xuc ban) OR (quoc ban)) anh vi cua tre*.