Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
van doan » van doanh, van toan, van hoan
sach ky » sac ky, sach y, sach ty
va doan » va doanh, va dan, va don
cua tre » cua te, cuu tre, cua triet
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: thu sach ky nang x hoi. hieu van ((tac tu) or (cac du)) ((va doan) OR (van doan)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang x hoi. hieu van ((tac tu) OR (cac du)) ((va doan) OR (van doan)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang x hoi. hieu van ((tac tu) or (cac du)) ((va doan) OR (van doan)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang x hoi. hieu van ((tac tu) or (cac du)) ((va doan) OR (van doan)) vi cua tre*.