Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, tu cach
te sach » toc sach
hieu ve » hieu va, hieu van
duc ban » duc van, dua ban, duc man
cua tre » cua te, cuu tre, cua triet
ve cam » ve cham, ve cac, va cam
vi cua » vai cua, di cua
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: ((tu sach) or (te sach)) ky nang x hoi. hieu ve cam ((duc ban) OR (duc tan)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) ky nang x hoi. hieu ve cam ((duc ban) OR (duc tan)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (te sach)) ky nang x hoi. hieu ve cam ((duc ban) OR (duc tan)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (te sach)) ky nang x hoi. hieu ve cam ((duc ban) OR (duc tan)) hanh vi cua tre*.