Perhaps you should try some spelling variations:
dinh tai » dinh toai, dinh tri, dinh thi
co sach » cuon sach, hoc sach
va dinh » van dinh, va kinh, va tinh
cac toc » cac toi, cac nuoc, cac thoi
cac tac » cac bac, cac dac, cac tai
hieu ve » hieu va, hieu van
cuc tre » duc tre, cua tre, cuu tre
hang xa » hoang xa, hang va, hang ca
ly hang » ly quang
bo sach » hoc sach

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((co sach) OR (bo sach)) ly hang xa hoi. hieu ve ((cac tac) or (cac toc)) va dinh tai cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((co sach) OR (bo sach)) ly hang xa hoi. hieu ve ((cac tac) OR (cac toc)) va dinh tai cuc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((co sach) OR (bo sach)) ly hang xa hoi. hieu ve ((cac tac) or (cac toc)) va dinh tai cuc tre".
• Adding a wildcard symbol may retrieve word variants: ((co sach) OR (bo sach)) ly hang xa hoi. hieu ve ((cac tac) or (cac toc)) va dinh tai cuc tre*.