Perhaps you should try some spelling variations:
trinh han » trinh quan
hieu soat » hieu suat, hieu hoat, hieu luat
tien soat » trien hoat, thien hoat, kiem soat
lang van » dang van, tang van, hoang van
van hieu » cao hieu
dung nam » dong nam, dung lam, sung nam
tan tien » toan tien, tran tien, tuan tien
nam tan » nam dan, nam tai, nam van

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( ((trinh han) or (tinh quang)) lang van hieu soat ) or ( tin dung nam tan tien soat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( ((trinh han) OR (tinh quang)) lang van hieu soat ) OR ( tin dung nam tan tien soat )).
• Adding a wildcard symbol may retrieve word variants: (( ((trinh han) or (tinh quang)) lang van hieu soat ) or ( tin dung nam tan tien soat ))*.