Perhaps you should try some spelling variations:
cong trong » cong thuong, duong trong, cong trinh
chieu sang » chieu sach, chieu xanh, nhieu tang
trong mach » trong cac, trong minh, trong anh
hieu lang » hieu quang, nhieu tang, hieu van
quang va » quang van, quan va, quang ma
mach van » mach vanh, bach van, cach van
va cong » tai cong, cua cong

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((chieu sang) or (hieu lang)) - tinh quang va cong trong mach van ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((chieu sang) OR (hieu lang)) - tinh quang va cong trong mach van ban*.