Perhaps you should try some spelling variations:
nghien thu » nghiem thuc, nghiep thuc, nghien cuu
van thanh » ban thanh, van tuan
thanh van » thanh san, thanh toan, thanh phan
cong hoc » dong hoc, cong hoa, cong coc
dan hoan » van hoan, dan hoat, dan toan
hoan hoc » hoa hoc, toan hoc, hoang hoa
so sach » so sanh, bo sach, co sach
hoi tap » hoc tap, hoi tai, hai tap
hoi van » hoi va, hoi dan, hai van
ma hoi » mai hoi, xa hoi, ma hoa

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 ((hoi tap) or (hoi dap)), nghien thu cong hoc dan hoan hoc ma hoi van thanh van~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((hoi tap) OR (hoi dap)), nghien thu cong hoc dan hoan hoc ma hoi van thanh van.
• Adding a wildcard symbol may retrieve word variants: so sach ((hoi tap) or (hoi dap)), nghien thu cong hoc dan hoan hoc ma hoi van thanh van*.