Perhaps you should try some spelling variations:
nghien cac » nghiep cach, nghien cuu, nghiep cay
danh nhan » doanh nhan, thanh nhan, benh nhan
toc sach » hoc sach, doc sach, thuoc sach
sach hoc » cach hoc, sach hoi, mach hoc
cac cong » cua cong
cong hoc » dong hoc, cong hoa, cong coc
hoc toan » hoc tan, hop toan, hoa toan
toan hoa » toan khoa, toan hoat, toan hoc
hoc xa » hoc ma

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach hoc tap, nghien cac cong hoc toan hoa hoc xa hoi ((ca nhan) or (danh nhan)) dan~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach hoc tap, nghien cac cong hoc toan hoa hoc xa hoi ((ca nhan) OR (danh nhan)) dan.
• Adding a wildcard symbol may retrieve word variants: toc sach hoc tap, nghien cac cong hoc toan hoa hoc xa hoi ((ca nhan) or (danh nhan)) dan*.