Perhaps you should try some spelling variations:
nghien thu » nghiem thuc, nghiep thuc, nghien cuu
sach hoi » sach doi, sach moi, cach thoi
cong hoc » dong hoc, cong hoa, cong coc
dan hoan » van hoan, dan hoat, dan toan
hoan hoc » hoa hoc, toan hoc, hoang hoa
khoi dan » hoi dan, khoi can, khoi dau
choi dan » hoi dan, hoa dan, hoi dap
su sach » so sach, vu sach
hoi tap » hoi dap, hoc tap, hoi tai
hoc mai » hoc ma, hoc dai, hoc bai

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach hoi tap, nghien thu cong hoc dan hoan hoc mai ((khoi dan) OR (choi dan)) thanh san~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach hoi tap, nghien thu cong hoc dan hoan hoc mai ((khoi dan) OR (choi dan)) thanh san".
• Adding a wildcard symbol may retrieve word variants: su sach hoi tap, nghien thu cong hoc dan hoan hoc mai ((khoi dan) OR (choi dan)) thanh san*.