Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hanh tai » thanh tai, hang tai, han tai
mai khoi » mai khoa, tai khoa, cac khoi
tai cua » thai cua, tai cuc, tri cua
truc va » thuc va, thuc vat, trung va
tu sach » thu sach, su sach, te sach
van cam » van nam, van lam, van cau
sach ky » sac ky, sach y, sach ty
mai hoi » dai hoi, lai hoi, mai doi
ky sang » ky nang, ky dang, ky tang
cua tre » cua te, cuu tre, cua triet

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 sang ((mai hoi) OR (mai khoi)). hieu van cam ((duc va) or (truc va)) hanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky sang ((mai hoi) OR (mai khoi)). hieu van cam ((duc va) OR (truc va)) hanh tai cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky sang ((mai hoi) OR (mai khoi)). hieu van cam ((duc va) or (truc va)) hanh tai cua tre*".