Perhaps you should try some spelling variations:
sach doi » sach hoi, sach moi, sach dao
dan khoa » dang khoa, da khoa, san khoa
khoa hoc » hoa hoc
phan van » thanh van, luan van, tran van
su sach » so sach, vu sach
doi tai » hoi tai, dai tai, doi tac
cuu mon » cuu mo, cuu mot, cuu cong
mon hoc » toan hoc, dong hoc
voi cac » loi cach
hoc xa » hoc ma
xa voi » xa hoi, ba voi, da voi

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach doi tai, nghien cuu mon hoc dan khoa hoc xa voi cac ((phan van) or (pham van))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach doi tai, nghien cuu mon hoc dan khoa hoc xa voi cac ((phan van) OR (pham van)).
• Adding a wildcard symbol may retrieve word variants: su sach doi tai, nghien cuu mon hoc dan khoa hoc xa voi cac ((phan van) or (pham van))*.