Perhaps you should try some spelling variations:
nghien cua » nghien cuu, nghiep cua, nghiep vua
doanh khoa » toan khoa
sach hoc » cach hoc, sach hoi, mach hoc
khoa hoc » hoa hoc
nhan dan » phan dau, gian dan
nhan tai » hang tai, van tai, toan tai
so sach » so sanh, bo sach, co sach
cua dan » cua dang, cua ban, ca dan
dan tri » dan thi, van tri, dan tai
hoc xa » hoc ma

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 hoc tap, nghien cua dan tri doanh khoa hoc xa hoi va ((nhan dan) OR (nhan tai))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach hoc tap, nghien cua dan tri doanh khoa hoc xa hoi va ((nhan dan) OR (nhan tai))".
• Adding a wildcard symbol may retrieve word variants: so sach hoc tap, nghien cua dan tri doanh khoa hoc xa hoi va ((nhan dan) OR (nhan tai))*.