Perhaps you should try some spelling variations:
thanh van » thanh san, thanh toan, thanh phan
thanh vai » thanh hai, thanh tai, thanh oai
hieu van » thien van, lieu va, hieu ve
tu sach » thu sach, su sach, te sach
duc ban » duc tan, duc van, dua ban
cam duc » cam xuc, cao duc, pham duc
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa

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 nang ma hoi. ((hieu van) or (hieu va)) cam duc ban ((thanh vai) OR (thanh van)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ma hoi. ((hieu van) OR (hieu va)) cam duc ban ((thanh vai) OR (thanh van)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ma hoi. ((hieu van) or (hieu va)) cam duc ban ((thanh vai) OR (thanh van)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ma hoi. ((hieu van) or (hieu va)) cam duc ban ((thanh vai) OR (thanh van)) cua tre*.