Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
tang van » dang van, hoang van, trong van
thai son » thai den, thai do, thai hoc
tu sach » thu sach, su sach, te sach
va thai » van thai, va tai, va tham
va danh » va dinh, va dan, va hanh
va vanh » va van, va hanh, va anh
hieu va » lieu va, hieu qua
van hoi » van hoa, van hoc, van hoe
ky tang » ky nang, ky dang, kho tang
cua te » cua tu

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