Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
sach thu » sach thue, sach thieu, sach tham
thu dang » thu hang, thu bang, thu dong
dang may » mang may, dang xay, dung may
hieu van » hieu va, thien van, lieu va
cua tre » cua te, cuu tre, cua triet
thuc va » thuc vat, thuc dan, thuc day
tu sach » thu sach, su sach, te sach
truc va » thuc vat, trung va
van cau » van dau, van hau, van chat
may hoi » may thoi, tay hoi, mai 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 thu dang may hoi. hieu van cau ((truc va) or (thuc va)) hanh vi ((cua tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thu dang may hoi. hieu van cau ((truc va) OR (thuc va)) hanh vi ((cua tre) OR (cau tren)).
• Adding a wildcard symbol may retrieve word variants: tu sach thu dang may hoi. hieu van cau ((truc va) or (thuc va)) hanh vi ((cua tre) or (cau tren))*.