Perhaps you should try some spelling variations:
thanh vai » thanh hai, thanh van, thanh oai
thanh tai » thanh hai, thanh toan, doanh tai
nam duoc » nam thuoc, da duoc, dat duoc
duoc ban » duc ban, quoc ban, buoc ban
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
va nam » van nam, ha nam, va nay
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 ky) or (cac ky)) nang x hoi. hieu va nam duoc ban ((thanh vai) OR (thanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (cac ky)) nang x hoi. hieu va nam duoc ban ((thanh vai) OR (thanh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (cac ky)) nang x hoi. hieu va nam duoc ban ((thanh vai) OR (thanh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (cac ky)) nang x hoi. hieu va nam duoc ban ((thanh vai) OR (thanh tai)) cua tre*.