Perhaps you should try some spelling variations:
sach doi » sach hoi, sach moi, sach dao
cuu cong » cua cong, thu cong, cac cong
cong cac » cuong cac, cong tac, cong cau
cac toan » cac khoan, hach toan, cac thanh
khoa hoc » hoa hoc
so sach » so sanh, bo sach, co sach
doi tap » doi tac, doi dap, doi tai
mai hoi » mai khoi, dai hoi, lai hoi
va phan » van phan, va phat, va phap
ma hoi » xa hoi, ma hoa, me hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach doi tap, nghien cuu cong cac toan khoa hoc ((ma hoi) or (mai hoi)) va phan tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach doi tap, nghien cuu cong cac toan khoa hoc ((ma hoi) OR (mai hoi)) va phan tu.
• Adding a wildcard symbol may retrieve word variants: so sach doi tap, nghien cuu cong cac toan khoa hoc ((ma hoi) or (mai hoi)) va phan tu*.