Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
khoa hoc » hoa hoc
van phan » van phong, van thanh, luan phan
phan dau » phan tu, hang dau
cuu mon » cuu mo, cuu mot, cuu cong
mon hoc » toan hoc, dong hoc
hoi van » hoi va, hoi dan, hai van
hoc da » hoc dan, hoc dai, hoc dat
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) or (hoc (sinh or minh))) hoc tap, nghien cuu mon hoc da khoa hoc xa hoi van phan dau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc (sinh OR minh))) hoc tap, nghien cuu mon hoc da khoa hoc xa hoi van phan dau.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (hoc (sinh or minh))) hoc tap, nghien cuu mon hoc da khoa hoc xa hoi van phan dau*.