Perhaps you should try some spelling variations:
nghien cac » nghiep cach, nghien cuu, nghiep cay
sach hoi » sach doi, sach moi, cach thoi
cac cong » cua cong
co sach » bo sach, cuon sach, hoc sach
hoi tap » hoi dap, hoc tap, hoi tai
co toan » co ton, so toan, cong toan
co tong » co trong, co dong, co ton
hoc hoc » hoc hoa, toc hoc, hoc hoi
va phap » va phat, ban phap
phap tu » phan tu, pham tu
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: co sach hoi tap, nghien cac cong ((co toan) or (co tong)) hoc hoc xa hoi va phap tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: co sach hoi tap, nghien cac cong ((co toan) OR (co tong)) hoc hoc xa hoi va phap tu.
• Adding a wildcard symbol may retrieve word variants: co sach hoi tap, nghien cac cong ((co toan) or (co tong)) hoc hoc xa hoi va phap tu*.