Perhaps you should try some spelling variations:
sach moi » sach doi, sach hoi, bach mai
khoa hoc » hoa hoc
tu sach » thu sach, su sach, te sach
moi tac » doi tac, moi tai, moi sach
cuu mon » cuu mo, cuu mot, cuu cong
ca pham » cau pham, ca cham, ha pham
hoc da » hoc dai, hoc dat, hoc dao
hoc xa » hoc ma
hoi ca » hoi cua, hoi cac, hoi cau

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach moi tac, nghien cuu mon ((hoc da) OR (hoc dan)) khoa hoc xa hoi ca pham van~.
• Adding a wildcard symbol may retrieve word variants: tu sach moi tac, nghien cuu mon ((hoc da) or (hoc dan)) khoa hoc xa hoi ca pham van*.