Perhaps you should try some spelling variations:
cong ngoc » cong ngo, hoang ngoc, cuong ngon
ngoc toan » ngoc tuan, ngoc tan, ngoc thanh
sanh doi » sach doi, thanh doi, anh doc
tinh doi » trinh doc, trinh do, tinh hoc
cuu cong » cua cong, thu cong, cac cong
khoa hoc » hoa hoc
nhan dan » phan dau, gian dan, nhan tai
va nhan » van nhan, ca nhan, va phan
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: so ((sanh doi) OR (tinh doi)) tap, nghien cuu cong ngoc toan khoa hoc xa hoi va nhan dan~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so ((sanh doi) OR (tinh doi)) tap, nghien cuu cong ngoc toan khoa hoc xa hoi va nhan dan".
• Adding a wildcard symbol may retrieve word variants: so ((sanh doi) OR (tinh doi)) tap, nghien cuu cong ngoc toan khoa hoc xa hoi va nhan dan*.