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
tu sach » thu sach, su sach, te sach
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: tu sach hoc tap, nghien cuu dong hoc khanh hoa hoc xa hoi va ((gian dan) OR (gian lang))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach hoc tap, nghien cuu dong hoc khanh hoa hoc xa hoi va ((gian dan) OR (gian lang))".
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cuu dong hoc khanh hoa hoc xa hoi va ((gian dan) OR (gian lang))*.