Perhaps you should try some spelling variations:
sach hoc » cach hoc, sach hoi, mach hoc
dan khoa » dang khoa, da khoa, san khoa
cua dinh » cua sinh, cua tinh, cua kinh
tu sach » thu sach, su sach, te sach
cuu mot » cua mot, cuu mo, huu mot
goc dan » hoc dan, soc dan, ngoc dang
ho cua » hoc cua, hoi cua, hoa cua

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 mot goc dan khoa ((hoc xa) or (hoc ma)) ho cua dinh van~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoc tap, nghien cuu mot goc dan khoa ((hoc xa) OR (hoc ma)) ho cua dinh van.
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cuu mot goc dan khoa ((hoc xa) or (hoc ma)) ho cua dinh van*.