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
su sach » so sach, vu sach
dan hoa » danh hoa, dan hoat, dan khoa
va nhan » van nhan, va phan, va nha
ma hoi » mai hoi, xa hoi, ma hoa

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 tong hoc dan hoa hoc ma hoi ((va nhan) OR (ca nhan)) dan~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach hoc tap, nghien cuu tong hoc dan hoa hoc ma hoi ((va nhan) OR (ca nhan)) dan".
• Adding a wildcard symbol may retrieve word variants: su sach hoc tap, nghien cuu tong hoc dan hoa hoc ma hoi ((va nhan) OR (ca nhan)) dan*.