Perhaps you should try some spelling variations:
sach hoc » cach hoc, sach hoi, mach hoc
hoc tang » hoc bang, hoc tan, hoc tieng
cua nhan » ca nhan, cua ngan, cua nha
nhan dan » phan dau, gian dan, nhan tai
tu sach » thu sach, su sach, te sach
hoi cua » hoi chuc
cuu co » huu co, cua co, cuu mo

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach hoc tap, nghien cuu co hoc tang ((khoa hoc) OR (hoa hoc)) xa hoi cua nhan dan~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach hoc tap, nghien cuu co hoc tang ((khoa hoc) OR (hoa hoc)) xa hoi cua nhan dan".
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cuu co hoc tang ((khoa hoc) OR (hoa hoc)) xa hoi cua nhan dan*.