Perhaps you should try some spelling variations:
danh nhan » doanh nhan, thanh nhan, dung nhan
sach hoc » cach hoc, sach hoi, mach hoc
cuu dong » cuu cong, cuu tong, cuu long
dong toc » dong hoc, dong tac, dong tot
san khoa » toan khoa, hang khoa, da khoa
khoa hoc » hoa hoc
tu sach » thu sach, su sach, te sach
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 dong toc san khoa hoc xa hoi ((danh nhan) or (benh nhan)) tao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoc tap, nghien cuu dong toc san khoa hoc xa hoi ((danh nhan) OR (benh nhan)) tao.
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cuu dong toc san khoa hoc xa hoi ((danh nhan) or (benh nhan)) tao*.