Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
va thanh » gia thanh, ban thanh, va tinh
su triet » su viet, su tien, ve triet
hieu ve » hieu va, hieu van
va hanh » van hanh, va danh, ban hanh
y nang » ly nang, v nang, may nang
dai su » dai sua, dai so, dan su
o hoc » co hoc, mo hoc, so hoc
ve am » va am

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

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