Perhaps you should try some spelling variations:
thanh toan » thanh hoa, thanh san, tinh toan
va thanh » gia thanh, ban thanh, va tinh
bang cau » hang cau, bang cac, nang cao
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, te sach, tu cach
cau luc » cau truc, cau phuc
cuc tre » duc tre, cua tre, cuc thue
van cau » van dau, van hau, van chat
ky bang » ky nang, ky dang, ke bang
su sach » so sach, vu sach
cuu tre » cua tre, cau tren, cau treo
luc va » duc va, tuc va, loc va

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) or (su sach)) ky bang cau hoi. hieu van cau luc va thanh toan ((cuc tre) OR (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky bang cau hoi. hieu van cau luc va thanh toan ((cuc tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ky bang cau hoi. hieu van cau luc va thanh toan ((cuc tre) OR (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky bang cau hoi. hieu van cau luc va thanh toan ((cuc tre) OR (cuu tre))*.