Perhaps you should try some spelling variations:
nghien cac » nghiep cach, nghien cuu, nghiep cay
doanh khoa » toan khoa
cong toan » cong tan, cong hoan, cong tuan
cac thoi » cac toi, cac hop, cac tro
thoi tap » toi tap, hoc tap, thoi dai
cac cong » cua cong
phan tai » pham tai, nhan tai, phan thi
hoc mai » hoc ma, hoc dai, hoc may
hoc bai » hoc dai, hoc giai
va phan » van phan, va phat, va phap

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu cac thoi tap, nghien cac cong toan doanh khoa ((hoc mai) OR (hoc bai)) hoi va phan tai~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu cac thoi tap, nghien cac cong toan doanh khoa ((hoc mai) OR (hoc bai)) hoi va phan tai".
• Adding a wildcard symbol may retrieve word variants: tu cac thoi tap, nghien cac cong toan doanh khoa ((hoc mai) OR (hoc bai)) hoi va phan tai*.