Perhaps you should try some spelling variations:
hoc thieu » hoc hien
hanh sinh » hanh tinh, hanh dinh, hinh sinh
va trong » va truong, va thong, va tuong
cong tan » cong tac, cong san, cong thanh
tan khan » tan khang, tan nhan, toan khoan
khan cap » khan ap, than cap, khoan cam
sinh va » sinh vat, tinh va, dinh 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 thieu) or (toc thieu)) tinh - hanh sinh va trong cong tan khan cap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc thieu) OR (toc thieu)) tinh - hanh sinh va trong cong tan khan cap*.