Perhaps you should try some spelling variations:
viet tech » viet sach
cong luan » tong luan, cong tuan, dong luan
cong tan » cong tac, cong san, cong thanh
dan phan » doan phan, dan chan, van phan
te viet » thi viet, tai viet
thong o » thong ke, thong tu, thong va
o dan » co dan, so dan, do dan

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

• Performing a fuzzy search may retrieve terms with similar spellings: te viet tech - thanh ((cong luan) or (cong tan)) thong o dan phan tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te viet tech - thanh ((cong luan) OR (cong tan)) thong o dan phan tu*.