Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
thuc van » thuc dan, thuc va, thuc hanh
hanh vai » hanh vi, hanh va, hanh tai
tu cach » tu cac
su sach » so sach, vu sach
vai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu cach) or (su sach)) ky nang x hoi. hieu van nam ((thuc van) OR (thuc vat)) hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (su sach)) ky nang x hoi. hieu van nam ((thuc van) OR (thuc vat)) hanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu cach) or (su sach)) ky nang x hoi. hieu van nam ((thuc van) OR (thuc vat)) hanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (su sach)) ky nang x hoi. hieu van nam ((thuc van) OR (thuc vat)) hanh vai cua tre*.