Perhaps you should try some spelling variations:
luan phan » luan van, luan hoan
phan hieu » phan kien, gian hieu, phan bien
hieu suat » hieu luat, hieu qua
dinh rang » dinh lang, dinh quang, dinh trong
rang hat » rang ham, dang hat, lang hat
van hieu » cao hieu
hieu hoa » tieu hoa, dieu hoa, hiep hoa
hat van » hoat van, ha van, hai van
tin » tinh

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tin dung luan phan hieu suat ) or ( dinh rang hat van hieu hoa ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tin dung luan phan hieu suat ) OR ( dinh rang hat van hieu hoa ))*.