Perhaps you should try some spelling variations:
sach hoc » cach hoc, sach hoi, mach hoc
hoc hang » hoc hanh, hoc bang, hoc tang
hang hoa » hang khoa, thanh hoa, hang va
nhan dan » phan dau, gian dan
nhan tai » hang tai, van tai, toan tai
so sach » so sanh, bo sach, co sach
cuu mon » cuu mo, cuu mot, cuu cong
mon hoc » toan hoc, dong hoc
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: so sach hoc tap, nghien cuu mon hoc hang hoa hoc xa hoi va ((nhan dan) or (nhan tai))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach hoc tap, nghien cuu mon hoc hang hoa hoc xa hoi va ((nhan dan) OR (nhan tai)).
• Adding a wildcard symbol may retrieve word variants: so sach hoc tap, nghien cuu mon hoc hang hoa hoc xa hoi va ((nhan dan) or (nhan tai))*.