Perhaps you should try some spelling variations:
nghien cac » nghiep cach, nghien cuu, nghiep cay
dac khanh » dat khanh, dan khanh, duc khanh
phong hoc » phong ho, thong hoc, phuong hoa
sach hoi » sach doi, cach thoi, hoach hoi
sach moi » sach doi, bach mai, sach bai
cac cong » cua cong
cong dac » cong tac, cong dan, cong cac
nhan va » nhan tai, nhan dan, nhan tao
hoc xa » hoc ma
hoi ca » hoi cua, hoi cac, hoi cau

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