Perhaps you should try some spelling variations:
sach tien » sach thieu
sach tren » sach tranh
ban hanh » ban hang
quoc ban » quoc bao, quoc lan, quoc quan
van cau » van dau, van hau, van chat
van cac » van hac, van bac, dan cac
nano xa » nano va, nano bac, nano cau
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua

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 tren) OR (sach tien)) nano xa hoi. hieu ((van cac) or (van cau)) quoc ban hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach tren) OR (sach tien)) nano xa hoi. hieu ((van cac) OR (van cau)) quoc ban hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach tren) OR (sach tien)) nano xa hoi. hieu ((van cac) or (van cau)) quoc ban hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach tren) OR (sach tien)) nano xa hoi. hieu ((van cac) or (van cau)) quoc ban hanh vi cua tre*.