Perhaps you should try some spelling variations:
hoc khanh » hoc nhanh, hoc thanh, hoc hanh
khanh hoa » thanh hoa, hang hoa
sach hoc » cach hoc, sach hoi, mach hoc
cuu dong » cuu cong, cuu tong, cuu long
dong hoc » dong co, dong luc
hoi benh » hoc benh, hoa benh, hoi binh
nhan dan » gian dan, nhan tai
phan dau » phan tu, hang dau
su sach » so sach, vu sach
hoc mai » hoc ma, hoc dai, hoc bai
mai hoi » mai khoi, dai hoi, lai hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach hoc tap, nghien cuu dong hoc khanh hoa hoc mai hoi benh ((nhan dan) OR (phan dau))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach hoc tap, nghien cuu dong hoc khanh hoa hoc mai hoi benh ((nhan dan) OR (phan dau))".
• Adding a wildcard symbol may retrieve word variants: su sach hoc tap, nghien cuu dong hoc khanh hoa hoc mai hoi benh ((nhan dan) OR (phan dau))*.