Perhaps you should try some spelling variations:
thieu sang » thieu khang, thieu quang, hieu lang
chieu sang » chieu sach, chieu xanh, hieu lang
dung thanh » duong thanh, dong thanh, dang thanh
thanh toan » thanh hoa, thanh san, tinh toan
trinh vat » trinh van, trinh luat, sinh vat
trinh va » trinh van, trinh ve, trinh vi
toan cau » toan cao, toan ban, toan tap

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

• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sang) OR (chieu sang)) - canh ((trinh va) OR (trinh vat)) ung dung thanh toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu sang) or (chieu sang)) - canh ((trinh va) OR (trinh vat)) ung dung thanh toan cau~".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sang) or (chieu sang)) - canh ((trinh va) OR (trinh vat)) ung dung thanh toan cau*.