Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
thanh van » thanh san, thanh toan, thanh phan
mach hoc » cach hoc, dich hoc, anh hoc
cong hoc » dong hoc, cong hoa, cong ho
cong coc » cong cuoc, cong cac, cong co
khoa hoc » hoa hoc
tu mach » tu cach, tu manh, tu hach
hoc dai » hoc dan
dai doi » dai hoi, dai moi, mai doi
doi van » do van, doi va, doi ban

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu mach hoc tap, nghien cuu ((cong hoc) or (cong coc)) toan khoa hoc dai doi van thanh van~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu mach hoc tap, nghien cuu ((cong hoc) OR (cong coc)) toan khoa hoc dai doi van thanh van.
• Adding a wildcard symbol may retrieve word variants: tu mach hoc tap, nghien cuu ((cong hoc) or (cong coc)) toan khoa hoc dai doi van thanh van*.