Perhaps you should try some spelling variations:
thanh toan » thanh hoa, thanh san, tinh toan
hieu van » hieu va, thien van, lieu va
bang cau » hang cau, bang cac, nang cao
cau luc » cau truc, cau phuc
cuc tre » duc tre, cuu tre, cuc thue
luc gia » luoc gia, duc gia, quoc gia
tu sach » thu sach, te sach, tu cach
van cau » van dau, van hau, van chat
ky bang » ky nang, ky dang, ke bang
su sach » so sach, vu sach
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: ((tu sach) or (su sach)) ky bang cau hoi. hieu van cau luc gia thanh toan ((cuc tre) OR (cua 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 gia thanh toan ((cuc tre) OR (cua 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 gia thanh toan ((cuc tre) OR (cua tre))".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky bang cau hoi. hieu van cau luc gia thanh toan ((cuc tre) OR (cua tre))*.