Perhaps you should try some spelling variations:
thiet tach » chiet tach, thien hach, thuat tach
nhung cong » dung cong, thong cong, hang cong
hoc thiet » hoc thieu, hoc thuyet, hoc hien
hanh hang » thanh hang, hang hang, hanh han
nang sang » nong san
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 tach - ((hanh hang) or (((nang sang) OR (nang song)))) va nhung cong tan van ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thiet tach - ((hanh hang) OR (((nang sang) OR (nang song)))) va nhung cong tan van ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc thiet tach - ((hanh hang) or (((nang sang) OR (nang song)))) va nhung cong tan van ban".
• Adding a wildcard symbol may retrieve word variants: hoc thiet tach - ((hanh hang) or (((nang sang) OR (nang song)))) va nhung cong tan van ban*.