Perhaps you should try some spelling variations:
nghien cua » nghien cuu, nghiep cua, nghiep vua
cong ngoc » cong ngo, hoang ngoc, cuong ngon
danh nhan » doanh nhan, thanh nhan, benh nhan
sach hoc » cach hoc, mach hoc, sach duoc
sach hoi » sach doi, sach moi, cach thoi
ngoc anh » ngu anh
anh khoa » doanh khoa, hang khoa
khoa hoc » hoa hoc
hoi danh » hop danh, hoi dan, hoc danh
nhan tai » hang tai, van tai, toan tai
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: thuat ((sach hoc) or (sach hoi)) tap, nghien cua cong ngoc anh khoa hoc xa hoi danh nhan tai~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat ((sach hoc) OR (sach hoi)) tap, nghien cua cong ngoc anh khoa hoc xa hoi danh nhan tai.
• Adding a wildcard symbol may retrieve word variants: thuat ((sach hoc) or (sach hoi)) tap, nghien cua cong ngoc anh khoa hoc xa hoi danh nhan tai*.