Perhaps you should try some spelling variations:
hoc thiet » hoc thieu, hoc thuyet, hoc hien
tao thiet » tai thiet, tay thiet, toan thiet
trinh van » trinh quan, trinh toan, dinh van
trinh han » trinh quan
dong cong » duong cong, dung cong, dang cong
cong tan » cong tac, cong san, cong thanh
tan van » tran van, tang van, luan van

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: ((hoc thiet) OR (tao thiet)) tach - hanh ((trinh van) OR (trinh han)) dong cong tan van ban~.
• Adding a wildcard symbol may retrieve word variants: ((hoc thiet) or (tao thiet)) tach - hanh ((trinh van) or (trinh han)) dong cong tan van ban*.