Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
thanh tung » thanh cong
dang trong » dung trong, dong trong, lang trong
hieu lang » chieu sang, nhieu tang, hieu van
trong van » trong cac
tung cao » nung cao, truong cao, trung cap
ban dau » bat dau, ban dan, van dau
ban can » ban dan, ban hang, ban hanh

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: doi ((hieu lang) OR (hieu quang)) - thanh tung cao dang trong van ((ban dau) OR (ban can))~.
• Adding a wildcard symbol may retrieve word variants: doi ((hieu lang) or (hieu quang)) - thanh tung cao dang trong van ((ban dau) or (ban can))*.