Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach hoc » cach hoc, sach hoi, mach hoc
cuu cong » cua cong, thu cong, cac cong
cong hoc » dong hoc, cong hoa, cong coc
nhan dan » phan dau, gian dan, nhan tai
hoc tan » hoc tang, hoc dan, hoc tai
va nhan » van nhan, ca nhan, va phan

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

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