Perhaps you should try some spelling variations:
than cua » nhan cua, thai cua, ban cua
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
hieu ve » hieu va, hieu van
sac ky » cac ky, sai ky
tu sac » tu sach, tu cac, tu san
o hoc » co hoc, mo hoc, so hoc
ve am » va am
o hoi » co hoi, o hai, o hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky nang ((o hoi) OR (o hoc)). hieu ve am thuc van hanh ((tai cuc) or (than cua)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky nang ((o hoi) OR (o hoc)). hieu ve am thuc van hanh ((tai cuc) OR (than cua)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky nang ((o hoi) OR (o hoc)). hieu ve am thuc van hanh ((tai cuc) or (than cua)) triet".
• Adding a wildcard symbol may retrieve word variants: tu sac ky nang ((o hoi) OR (o hoc)). hieu ve am thuc van hanh ((tai cuc) or (than cua)) triet*.