Perhaps you should try some spelling variations:
doanh khong » doanh thuong, doanh khoa, doanh chung
thuoc sach » hoc sach, nuoc sach, thuat sach
nghien cua » nghien cuu, nghiep cua, nghiep vua
hoa doanh » toan doanh, hoa dan
khong hoc » khung hoc, thong hoc, khong thuoc
sach hoc » cach hoc, sach hoi, mach hoc
cong hoa » dong hoa, dong hoc, hang hoa
nhan tao » nhan tai, nhan dan
hoc mai » hoc ma, hoc dai, hoc bai
mai hoi » mai khoi, dai hoi, lai hoi
nhan va » nhan tai, nhan dan, phan van

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc sach hoc tap, nghien cua cong hoa doanh khong hoc mai hoi va ((nhan va) or (nhan tao))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach hoc tap, nghien cua cong hoa doanh khong hoc mai hoi va ((nhan va) OR (nhan tao)).
• Adding a wildcard symbol may retrieve word variants: thuoc sach hoc tap, nghien cua cong hoa doanh khong hoc mai hoi va ((nhan va) or (nhan tao))*.