Perhaps you should try some spelling variations:
sach duoc » sach nuoc, sach dao, sach dung
dan khoat » dan hoat, dan khoa, san khoa
khoat hoc » khoa hoc, hoa hoc, chat hoc
cach hoc » cach thuc, cach thoi, dich hoc
dan nhan » danh nhan, dan chan, van nhan
nhan dan » phan dau, gian dan, nhan tai
hoi dan » hoc dan, hoi dap, thoi dai
hoc xa » hoc ma
hoa » khoa
khoat » kkhoat

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc ((sach duoc) or (cach hoc)) tap, nghien cuu van hoa dan khoat hoc xa hoi dan nhan dan~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach duoc) OR (cach hoc)) tap, nghien cuu van hoa dan khoat hoc xa hoi dan nhan dan.
• Adding a wildcard symbol may retrieve word variants: toc ((sach duoc) or (cach hoc)) tap, nghien cuu van hoa dan khoat hoc xa hoi dan nhan dan*.