Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
van sach » ban sach, van hach, ngan sach
va thanh » ban thanh, va tinh, le thanh
sach ky » sac ky, sach y, sach ty
va sach » va cach, a sach, vu sach
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. hieu ((va sach) OR (van sach)) nuoc ((va thanh) or (gia thanh)) dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang x hoi. hieu ((va sach) OR (van sach)) nuoc ((va thanh) OR (gia thanh)) dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang x hoi. hieu ((va sach) OR (van sach)) nuoc ((va thanh) or (gia thanh)) dai cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang x hoi. hieu ((va sach) OR (van sach)) nuoc ((va thanh) or (gia thanh)) dai cua tre*.