Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach hoc » cach hoc, sach hoi, mach hoc
hoc tang » hoc bang, hoc tieng, hoc trong
khoa hoc » hoa hoc
nhan dan » phan dau, gian dan, nhan tai
cuu mot » cua mot, cuu mo, huu mot
hoc tan » hoc dan, hoc tai, hoc can
va nhan » van nhan, ca nhan, va phan
hoc xa » hoc ma

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 mot ((hoc tan) or (hoc tang)) khoa hoc xa hoi va nhan dan~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach hoc tap, nghien cuu mot ((hoc tan) OR (hoc tang)) khoa hoc xa hoi va nhan dan.
• Adding a wildcard symbol may retrieve word variants: toc sach hoc tap, nghien cuu mot ((hoc tan) or (hoc tang)) khoa hoc xa hoi va nhan dan*.