Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, nam thu, nam tu
hanh tai » thanh tai, hang tai, han tai
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
va hanh » van hanh, va thanh, va danh
tai cua » thai cua, tai cuc, tri cua
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: ((te sach) OR (toc sach)) ky lang xa hoi. lieu va ((nam thuc) or (am thuc)) va hanh tai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky lang xa hoi. lieu va ((nam thuc) OR (am thuc)) va hanh tai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ky lang xa hoi. lieu va ((nam thuc) or (am thuc)) va hanh tai cua te".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ky lang xa hoi. lieu va ((nam thuc) or (am thuc)) va hanh tai cua te*.