Perhaps you should try some spelling variations:
sang trong » lang trong, mang trong, nang trong
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 qua » quang cua, quang tuan, quang xuan
mach toan » manh toan, hach toan, mach tuan
qua sang » qua song, qua san, bua sang
toan ban » van ban

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 qua sang trong mach toan ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((chieu sang) OR (hieu lang)) - tinh quang qua sang trong mach toan ban*.