Perhaps you should try some spelling variations:
nang dai » nang tai, lang dai, nang cai
hanh hai » thanh hai, nhanh hai, hang hai
nang dau » hang dau, xang dau, nang du
su sach » so sach, vu sach
hai cua » thai cua, dai cua, hoi cua
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
ve cam » ve cham, ve cac, va cam
tuc va » thuc va, truc va, duc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty ((nang dai) or (nang dau)) hoi. hieu ve cam ((tuc va) OR (tuc xa)) hanh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((nang dai) OR (nang dau)) hoi. hieu ve cam ((tuc va) OR (tuc xa)) hanh hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((nang dai) or (nang dau)) hoi. hieu ve cam ((tuc va) OR (tuc xa)) hanh hai cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ty ((nang dai) or (nang dau)) hoi. hieu ve cam ((tuc va) OR (tuc xa)) hanh hai cua tre*.