Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nang van » dang van, tang van, lang van
hieu van » hieu va, thien van, lieu va
hanh dai » hanh tai, hanh dao, vanh dai
va triet » va thiet, va trien, ve triet
tu sach » thu sach, su sach, te sach
van hoi » van hoa, van hoc, van hoe
thu va » thuc va, thue va, thu ha
dai va » mai va

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