Perhaps you should try some spelling variations:
sach doi » sach hoi, sach moi, sach dao
cuu cong » cua cong, thu cong, cac cong
coc phan » co phan, hoc phan, doc phan
cac phan » cac nhan, cao phan, cap phan
loai hoc » logic hoc, loai khoa, dai hoc
nhan dan » phan dau, gian dan, nhan tai
tu sach » thu sach, su sach, te sach
doi tai » hoi tai, dai tai, doi tac
hoc mai » hoc ma, hoc dai, hoc bai
mai hoi » mai khoi, dai hoi, lai hoi
hoi ca » hoi cua, hoi cac, hoi cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach doi tai, nghien cuu cong ((coc phan) OR (cac phan)) loai hoc mai hoi ca nhan dan~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach doi tai, nghien cuu cong ((coc phan) OR (cac phan)) loai hoc mai hoi ca nhan dan".
• Adding a wildcard symbol may retrieve word variants: tu sach doi tai, nghien cuu cong ((coc phan) OR (cac phan)) loai hoc mai hoi ca nhan dan*.