Perhaps you should try some spelling variations:
nghien cac » nghiep cach, nghien cuu, nghiep cay
van thanh » ban thanh, van tuan
thanh van » thanh san, thanh toan, thanh phan
thu mach » thu sach, thuat mach, thu hoach
mach hoc » cach hoc, dich hoc, anh hoc
cac cong » cua cong
khoa hoc » hoa hoc
cong so » cong san, cong hoa
so toan » so tan, so than, bao toan
xua hai » qua hai, cua hai, xuan thai
xa hai » xa thai, xa hoi, xa dai

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

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