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
cam qua » cau qua, cac qua, cay qua
van cam » van nam, van lam, van cau
sach ky » sac ky, sach ty, sach kem
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) OR (sach y)) nang ma hoi. hieu van cam qua quan ((thanh vai) or (thanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach y)) nang ma hoi. hieu van cam qua quan ((thanh vai) OR (thanh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) OR (sach y)) nang ma hoi. hieu van cam qua quan ((thanh vai) or (thanh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) OR (sach y)) nang ma hoi. hieu van cam qua quan ((thanh vai) or (thanh tai)) cua tre*.