Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hanh tai » thanh tai, hang tai, han tai
tai cua » thai cua, tai cuc, tri cua
thuc va » thuc vat, thuc dan, thuc day
thuc xa » thuc xay, tuc xa, thuc ha
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
cua tre » cua te, cuu tre, cua triet
ma hoi » xa hoi, ma hoa, me hoi

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