Perhaps you should try some spelling variations:
thanh toan » thanh hoa, thanh san, tinh toan
su triet » su viet, su tien, ve triet
hieu van » hieu va, thien van, lieu va
thanh va » thanh van, hanh va, thanh ha
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
van cac » van hac, van cau, van bac
hoang o » hoang b, hoang son, hoang bao
cac tac » cac toc, cac bac, cac dac
tac xa » tuc xa, tac da

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 ty ((hoang o) OR (hoang _)) hai. hieu van cac tac xa ((thanh va) or (thanh toan)) su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((hoang o) OR (hoang _)) hai. hieu van cac tac xa ((thanh va) OR (thanh toan)) su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((hoang o) OR (hoang _)) hai. hieu van cac tac xa ((thanh va) or (thanh toan)) su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((hoang o) OR (hoang _)) hai. hieu van cac tac xa ((thanh va) or (thanh toan)) su triet*.