Perhaps you should try some spelling variations:
cong thuoc » cong thuc, dong thuoc, long thuoc
thanh hoa » thanh pho
phan phan » phap phan, phan phat, than phan
sach hoc » cach hoc, sach hoi, mach hoc
cuu cong » cua cong, thu cong, cac cong
ninh hoa » minh hoa, tinh hoa, hinh hoa
hoa phan » hoa dan, co phan
phan van » pham van, thanh van, luan van
tu sach » thu sach, su sach, te sach

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 hoc tap, nghien cuu cong thuoc ((ninh hoa) or (thanh hoa)) hoc ma hoa phan phan van~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoc tap, nghien cuu cong thuoc ((ninh hoa) OR (thanh hoa)) hoc ma hoa phan phan van.
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cuu cong thuoc ((ninh hoa) or (thanh hoa)) hoc ma hoa phan phan van*.