Perhaps you should try some spelling variations:
thanh vai » thanh hai, thanh van, thanh tai
van thanh » ban thanh, van tuan
cham hoc » cham soc, chat hoc, cham hoi
qua cham » qua hai, qua cac, va cham
vai cua » dai cua, hai cua, lai cua
hoc van » hoc dan, hoc va, hoc vat
sang ma » tang ma, sang tao, mang may
sach ty » sach tu, sach thu, xach tay
nang ma » tang ma, nang cao, mang may
cua tre » cua te, cuu tre, cua triet

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te ((sach ty) OR (sach y)) ((nang ma) or (sang ma)) hoa. hieu qua cham hoc van thanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ty) OR (sach y)) ((nang ma) OR (sang ma)) hoa. hieu qua cham hoc van thanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ty) OR (sach y)) ((nang ma) or (sang ma)) hoa. hieu qua cham hoc van thanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: te ((sach ty) OR (sach y)) ((nang ma) or (sang ma)) hoa. hieu qua cham hoc van thanh vai cua tre*.