Perhaps you should try some spelling variations:
sach hoc » cach hoc, sach hoi, mach hoc
cuu tong » cuu cong, cuu tinh, huu tung
tong hoc » tuong hoc, thong hoc, trong hoc
nhan dan » phan dau, nhan tai
gian dan » gian lang
so sach » so sanh, bo sach, co sach
dan hoa » danh hoa, dan hoat, dan khoa
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 tap, nghien cuu tong hoc dan hoa hoc mai hoi dan ((nhan dan) or (gian dan))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach hoc tap, nghien cuu tong hoc dan hoa hoc mai hoi dan ((nhan dan) OR (gian dan)).
• Adding a wildcard symbol may retrieve word variants: so sach hoc tap, nghien cuu tong hoc dan hoa hoc mai hoi dan ((nhan dan) or (gian dan))*.