Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
dang hai » dang khai, hang hai, dung hai
sach ky » sac ky, sach y, sach ty
van bac » van bao, van hac, dan bac
va dang » van dang, va nang, va lang
hai cua » thai cua, dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky nang x hoi. thien ((van bac) or (van ban)) nuoc va dang hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang x hoi. thien ((van bac) OR (van ban)) nuoc va dang hai cua tre.
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang x hoi. thien ((van bac) or (van ban)) nuoc va dang hai cua tre*.