Perhaps you should try some spelling variations:
nghien cua » nghien cuu, nghiep cua, nghiep vua
cua cuong » cua cong, cua huong, cua truong
cuong cac » luong cac, cong cac, trong cac
cac khanh » cac thanh, cach nhanh, khac khanh
khanh hoa » thanh hoa, hang hoa
sach hoc » cach hoc, sach hoi, mach hoc
nhan tao » nhan tai, nhan dan
tu sach » thu sach, su sach, te sach
nhan va » nhan tai, nhan dan, phan van
hoc xa » hoc ma

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoc tap, nghien cua cuong cac khanh hoa hoc xa hoi va ((nhan va) OR (nhan tao))~.
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cua cuong cac khanh hoa hoc xa hoi va ((nhan va) or (nhan tao))*.