Perhaps you should try some spelling variations:
nghien huu » nghien cuu, nguyen huu, nhiem huu
ngan khong » nganh khong, nhan khong, ngan hang
khong hoc » khung hoc, thong hoc, khong thuoc
tung luc » trung luc, truong luc, tung buoc
luc ngan » luc nganh, luc nhan, luat ngan
nhan dan » phan dau, gian dan, nhan tai
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
hoi tap » hoi dap, hoc tap, hoi tai
xa nhan » ca nhan, va nhan, xa phan
hoa » khoa

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) or (su sach)) hoi tap, nghien huu tung luc ngan khong hoc ma hoa xa nhan dan~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) hoi tap, nghien huu tung luc ngan khong hoc ma hoa xa nhan dan.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) hoi tap, nghien huu tung luc ngan khong hoc ma hoa xa nhan dan*.