Perhaps you should try some spelling variations:
thuc dan » thuc hanh, thuc vat
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
ve nam » he nam, va nam, le nam
nang o » nang co, nang ho, nang ro
hai ca » hai cua, hai ba, hai va
o hoi » co hoi, o hoc, o hai

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 ky nang o hoi. hieu ve nam ((thuc dan) OR (hoc dan)) manh ((hai ca) or (bai ca)) viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang o hoi. hieu ve nam ((thuc dan) OR (hoc dan)) manh ((hai ca) OR (bai ca)) viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang o hoi. hieu ve nam ((thuc dan) OR (hoc dan)) manh ((hai ca) or (bai ca)) viet*".