Perhaps you should try some spelling variations:
sach hoc » cach hoc, sach hoi, mach hoc
dong hoc » dong luc
pho khoa » phu khoa, pha khoa, tho khoa
khoa hoc » hoa hoc
nhan dan » phan dau, gian dan, nhan tai
su sach » so sach, vu 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: su sach hoc tap, nghien cuu ((dong hoc) or (dong co)) pho khoa hoc xa hoi va nhan dan~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach hoc tap, nghien cuu ((dong hoc) OR (dong co)) pho khoa hoc xa hoi va nhan dan.
• Adding a wildcard symbol may retrieve word variants: su sach hoc tap, nghien cuu ((dong hoc) or (dong co)) pho khoa hoc xa hoi va nhan dan*.