Perhaps you should try some spelling variations:
trinh quang » tinh quang, trinh quan, tranh quang
quang luan » quan luan, quang tuan, quang uan
hieu soat » hieu suat, hieu hoat, hieu luat
bien soan » bien so
van hieu » cao hieu
nang sua » nang suat, nang cua, nang su
nang dua » nang du, nang suat, nang quan
doi bien » doi dien, voi bien, doi hien

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( trinh quang luan van hieu soat ) or ( tin ((nang sua) or (nang dua)) doi bien soan ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh quang luan van hieu soat ) OR ( tin ((nang sua) OR (nang dua)) doi bien soan )).
• Adding a wildcard symbol may retrieve word variants: (( trinh quang luan van hieu soat ) or ( tin ((nang sua) or (nang dua)) doi bien soan ))*.