Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
sach kem » hanh kem
va thanh » gia thanh, ban thanh, va tinh
truc va » thuc va, thuc vat, trung va
van hau » van ha, van hai, van dau
van cau » van dau, van chat, toan cau
nang co » nang cao, nang doc, nang noi
cua tre » cua te, cuu tre, cua triet
co hoi » co hoc, co loi
sac ky » cac ky, sai ky

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 kem) or (sac ky)) nang co hoi. hieu ((van cau) OR (van hau)) truc va thanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach kem) OR (sac ky)) nang co hoi. hieu ((van cau) OR (van hau)) truc va thanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach kem) or (sac ky)) nang co hoi. hieu ((van cau) OR (van hau)) truc va thanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach kem) or (sac ky)) nang co hoi. hieu ((van cau) OR (van hau)) truc va thanh dai cua tre*.