Perhaps you should try some spelling variations:
nghien cua » nghien cuu, nghiep cua, nghiep vua
sach hoi » sach doi, sach moi, cach thoi
cong hoc » dong hoc, cong hoa, cong coc
hoc phan » hoc dan, hoc pho
phan hoa » phan loai, phan phoi, phan hong
gian dan » gian lang
tu sach » thu sach, su sach, te sach
va gian » va gianh, van gian, va giai

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 dap, nghien cua cong hoc phan hoa ((hoc xa) or (hoc ma)) hoi va gian dan~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoi dap, nghien cua cong hoc phan hoa ((hoc xa) OR (hoc ma)) hoi va gian dan.
• Adding a wildcard symbol may retrieve word variants: tu sach hoi dap, nghien cua cong hoc phan hoa ((hoc xa) or (hoc ma)) hoi va gian dan*.