Perhaps you should try some spelling variations:
trinh xuong » trinh duong, trinh huong, trinh phuong
xuong quan » xuong quang, luong quan, cuong quan
kiem soat » kiem toan
hieu hoat » hieu hoa, thien hoat, hieu suat
hieu luat » hieu qua
quan van » luan van, quan va, quan luan
hieu so » thieu so

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

• If you are trying to use Boolean operators, they must be ALL CAPS: trinh xuong quan van ((((hieu so) OR (kiem soat))) OR (((hieu hoat) OR (hieu luat))))~.
• Adding a wildcard symbol may retrieve word variants: trinh xuong quan van ((((hieu so) or (kiem soat))) or (((hieu hoat) or (hieu luat))))*.