Perhaps you should try some spelling variations:
thanh toan » thanh hoa, thanh san, tinh toan
thanh tai » thanh hai, doanh tai, thanh san
nang dau » hang dau, xang dau, nang du
cac luc » cau luc, coc luc, cac nuoc
luc van » luoc van, luu van, duc van
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach kem
hieu ve » hieu va, hieu van
dau hoi » cau hoi, dai hoi, dan hoi
sach ty » sach y, sach tu, sach thu
ve cac » va cac, vien cac

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