Perhaps you should try some spelling variations:
ve triet » va trien, su triet
dau thuc » dan thuc, dai thuc, dam thuc
hanh tai » thanh tai, hang tai, han tai
toc sach » hoc sach, doc sach, thuoc sach
hanh dai » hanh dao, vanh dai, thanh dat
hieu van » hieu va, thien van, lieu va
thuc va » thuc vat, thuc dan, thuc day
van dau » van dao, phan dau
nang o » nang co, nang ho, nang ro
o hoc » co hoc, mo hoc, so hoc

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

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