Perhaps you should try some spelling variations:
cong tac » cong ty
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
sach sy » sach y, sach ty, sach hay
sy cong » so cong, ky cong, ly cong
tac hoi » tao hoi, tay hoi, tac hai
van cam » van nam, van lam, van cau
hanh va » hanh vi
cua tre » cua te, cuu tre, cua triet
xuc va » tuc va, luc va, xac 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 sy cong tac hoi. hieu van cam ((xuc va) or (duc va)) ((hanh va) or (hang va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach sy cong tac hoi. hieu van cam ((xuc va) OR (duc va)) ((hanh va) OR (hang va)) cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach sy cong tac hoi. hieu van cam ((xuc va) or (duc va)) ((hanh va) or (hang va)) cua tre*.