Perhaps you should try some spelling variations:
hanh tai » thanh tai, hang tai, han tai
tu sach » thu sach, su sach, te sach
cac tuc » cac toc, cac tu, cac tac
van tai » von tai, van tuan
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ky danh » ky anh
ky dang » ky nang
tuc va » thuc va, truc va, tuc xa
ve cac » va cac, vien cac

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 dang) OR (ky danh)) mai hoi. hieu ve cac tuc va ((hanh tai) or (van tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky dang) OR (ky danh)) mai hoi. hieu ve cac tuc va ((hanh tai) OR (van tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky dang) OR (ky danh)) mai hoi. hieu ve cac tuc va ((hanh tai) or (van tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky dang) OR (ky danh)) mai hoi. hieu ve cac tuc va ((hanh tai) or (van tai)) cua tre*.