Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
hoc thiet » hoc thuyet, hoc hien, toc thieu
hoc thieu » toc thieu, hoc hien
hanh hang » thanh hang, hang hang, hanh han
nang hang » nang sang, hang hang, cang thang
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.

• Performing a fuzzy search may retrieve terms with similar spellings: ((hoc thiet) OR (hoc thieu)) tach - ((hanh hang) or (nang hang)) va nhung cong tan van ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc thiet) OR (hoc thieu)) tach - ((hanh hang) OR (nang hang)) va nhung cong tan van ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc thiet) OR (hoc thieu)) tach - ((hanh hang) or (nang hang)) va nhung cong tan van ban".
• Adding a wildcard symbol may retrieve word variants: ((hoc thiet) OR (hoc thieu)) tach - ((hanh hang) or (nang hang)) va nhung cong tan van ban*.