Perhaps you should try some spelling variations:
khoi thanh » hoi thanh, khoan thanh, khong thanh
sinh khoi » sinh khoa, sinh hoc, sinh thai
thanh hoa » thanh pho
sach hoc » cach hoc, sach hoi, mach hoc
cuu sinh » cuu tinh, cua sinh, cho sinh
tu sach » thu sach, su sach, te sach
va nhan » van nhan, ca nhan, va phan
hoc xa » hoc ma

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 hoc tap, nghien cuu sinh khoi thanh hoa hoc xa hoi ((va nhan) or (benh nhan)) van~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoc tap, nghien cuu sinh khoi thanh hoa hoc xa hoi ((va nhan) OR (benh nhan)) van.
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cuu sinh khoi thanh hoa hoc xa hoi ((va nhan) or (benh nhan)) van*.