Perhaps you should try some spelling variations:
sach hoc » cach hoc, mach hoc, sach duoc
sach hoi » sach doi, sach moi, cach thoi
khoa hoc » hoa hoc
nhan dan » phan dau, gian dan, nhan tai
cuu mot » cua mot, cuu mo, huu mot
mot hoc » mon hoc, mo hoc, mot goc
hoc da » hoc dan, hoc dai, hoc dat
hoc xa » hoc ma
hoi ca » hoi cua, hoi cac, hoi cau

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc ((sach hoc) OR (sach hoi)) tap, nghien cuu mot hoc da khoa hoc xa hoi ca nhan dan~".
• Adding a wildcard symbol may retrieve word variants: thuoc ((sach hoc) OR (sach hoi)) tap, nghien cuu mot hoc da khoa hoc xa hoi ca nhan dan*.