Perhaps you should try some spelling variations:
nghien cac » nghiep cach, nghien cuu, nghiep cay
hoan thanh » hoang thanh, ban thanh, van thanh
cong hoan » cong hoa, dong hoa, cong san
thanh hoa » thanh pho
cac cong » cua cong
hoi benh » hoc benh, hoa benh, hoi binh
nhan dan » phan dau, gian dan, nhan tai
cac hoc » cach hoc, cac hop, bac hoc
ma hoi » mai hoi, xa hoi, ma hoa

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 hoc tap, nghien cac cong hoan thanh hoa hoc ma hoi benh ((nhan dan) or (phan tu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu cac hoc tap, nghien cac cong hoan thanh hoa hoc ma hoi benh ((nhan dan) OR (phan tu)).
• Adding a wildcard symbol may retrieve word variants: tu cac hoc tap, nghien cac cong hoan thanh hoa hoc ma hoi benh ((nhan dan) or (phan tu))*.