Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
nang hoc » nang doc, nang luc, dong hoc
hanh dai » hanh tai, hanh dao, vanh dai
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
nang ho » nang co, tang ho, nang cao
van am » van nam, van lam, van dam
dai su » dai sua, dai so, dan su

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

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