Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
hanh vai » hanh vi, hanh va, hanh tai
hieu van » hieu va, thien van, lieu va
tu sach » su sach, te sach, tu cach
vai cua » dai cua, hai cua, lai cua
thuc va » thuc vat, thuc dan, thuc day
van cam » van nam, van lam, van cau
hang xa » hoang xa, hang va, hang ca
ty hang » ly hang, ty xang, thi hang
cua tre » cua te, cuu tre, cua triet
luc va » duc va, tuc va, loc va

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) or (thu sach)) ty hang xa hoi. hieu van cam ((luc va) or (thuc va)) hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ty hang xa hoi. hieu van cam ((luc va) OR (thuc va)) hanh vai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ty hang xa hoi. hieu van cam ((luc va) or (thuc va)) hanh vai cua tre*.