Perhaps you should try some spelling variations:
nghien huu » nghien cuu, nguyen huu, nhiem huu
doanh nang » doanh sang, doanh nhung, doanh quang
sach hoc » cach hoc, mach hoc, sach duoc
sach hoi » sach doi, sach moi, cach thoi
ha doanh » hoa doanh, nha doanh, va doanh
cau pham » cau cham, cau phan, cau phap
hoi cau » hoi chu, hoc cau, hoa cau
son ha » son hai, son la
luc va » duc va, tuc va, loc va
va hoi » xa hoi, va hoc, va 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 ((sach hoc) or (sach hoi)) tap, nghien huu son ha doanh nang luc va hoi cau pham van~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach hoc) OR (sach hoi)) tap, nghien huu son ha doanh nang luc va hoi cau pham van.
• Adding a wildcard symbol may retrieve word variants: tu ((sach hoc) or (sach hoi)) tap, nghien huu son ha doanh nang luc va hoi cau pham van*.