Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
thanh vai » thanh hai, thanh van, thanh oai
hieu van » hieu va, thien van, lieu va
van cau » van dau, van hau, van chat
qua ban » cua ban, qua quan
sach ky » sac ky, sach y, sach kem
nang ma » tang ma, sang ma, nang cao
sach ty » sach y, sach tu, sach thu
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: su ((sach ky) or (sach ty)) nang ma hoi. hieu van cau qua ban ((thanh vai) OR (thanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach ty)) nang ma hoi. hieu van cau qua ban ((thanh vai) OR (thanh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) or (sach ty)) nang ma hoi. hieu van cau qua ban ((thanh vai) OR (thanh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sach ty)) nang ma hoi. hieu van cau qua ban ((thanh vai) OR (thanh tai)) cua tre*.