Perhaps you should try some spelling variations:
quang phan » quang chan, quang phat, quang thanh
theo hieu » theo chieu, theo tieu, thien hieu
hieu lang » chieu sang, hieu quang, nhieu tang
tong cong » trong cong, cong cong, dung cong
vang phan » van phan, nang phan, va phan
tung cao » truong cao, trung cap, quang cao
nung cao » nang cao, nhung cau, quang cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: theo hieu lang - thanh ((tung cao) or (nung cao)) tong cong ((vang phan) OR (quang phan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo hieu lang - thanh ((tung cao) OR (nung cao)) tong cong ((vang phan) OR (quang phan)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo hieu lang - thanh ((tung cao) or (nung cao)) tong cong ((vang phan) OR (quang phan)) cau".
• Adding a wildcard symbol may retrieve word variants: theo hieu lang - thanh ((tung cao) or (nung cao)) tong cong ((vang phan) OR (quang phan)) cau*.