Perhaps you should try some spelling variations:
tranh nghien » trinh nghien, tron nghien, trong nghien
sach doanh » sach danh, cac doanh, san doanh
sach tranh » canh tranh
nghiep tu » nghiep vu, nghiep vua, nghiep cua
nghien d » nghiem d, nghien o, nghiem de
so sach » so sanh, bo sach, co sach
su sach » vu sach
tu hoc » te hoc
d hoc » du hoc, ad hoc, de hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( so sach doanh nghiep tu hoc ) or ( su sach tranh nghien d hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( so sach doanh nghiep tu hoc ) OR ( su sach tranh nghien d hoc )).
• Adding a wildcard symbol may retrieve word variants: (( so sach doanh nghiep tu hoc ) or ( su sach tranh nghien d hoc ))*.