Perhaps you should try some spelling variations:
vat thanh » dat thanh, gat thanh, tat thanh
thanh ky » hanh ky, thanh tay, thanh huy
hieu van » hieu va, thien van, lieu va
cau thuc » cau truc, cuu thuc, can thuc
xay hoi » xa hoi, tay hoi, cay phoi
van cau » van dau, van hau, van chat
va cua » va chua, via cua, ma cua
ca cua » co cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu ((thanh ky) OR (than ky)) van xay hoi. hieu van cau thuc vat thanh ((va cua) or (ca cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu ((thanh ky) OR (than ky)) van xay hoi. hieu van cau thuc vat thanh ((va cua) OR (ca cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu ((thanh ky) OR (than ky)) van xay hoi. hieu van cau thuc vat thanh ((va cua) or (ca cua)) tre".
• Adding a wildcard symbol may retrieve word variants: vu ((thanh ky) OR (than ky)) van xay hoi. hieu van cau thuc vat thanh ((va cua) or (ca cua)) tre*.