Perhaps you should try some spelling variations:
sach hoc » cach hoc, sach hoi, sach duoc
mach hoc » cach hoc, dich hoc, anh hoc
cuu tong » cuu cong, cuu tinh, huu tung
tong hoc » tuong hoc, thong hoc, trong hoc
dan hoat » van hoa, dan hoc, danh hoa
hoat hoc » hoa hoc, hoat ho, khoa hoc
dan phan » doan phan, dan chan, van phan
phan dau » phan tu, hang dau
hoc mai » hoc ma, hoc dai, hoc bai
mai hoi » mai khoi, dai hoi, lai hoi
hoi dan » hoa dan, hoi dap, thoi dai

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) or (mach hoc)) tap, nghien cuu tong hoc dan hoat hoc mai hoi dan phan dau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((sach hoc) OR (mach hoc)) tap, nghien cuu tong hoc dan hoat hoc mai hoi dan phan dau.
• Adding a wildcard symbol may retrieve word variants: so ((sach hoc) or (mach hoc)) tap, nghien cuu tong hoc dan hoat hoc mai hoi dan phan dau*.