Perhaps you should try some spelling variations:
cau theo » cau thi, cau tao
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, nam thu, nam tu
vai cau » va cau, van cau, vai cac
dan vai » dan va, dan tai, dan vat
toc sac » toc san, hoc sach, doc sach
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
hieu va » lieu va, hieu qua
va dan » ca dan, va dao, va dau

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sac) OR (toc sach)) ky lang xa hoi. hieu va ((nam thuc) or (am thuc)) va dan vai cau theo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sac) OR (toc sach)) ky lang xa hoi. hieu va ((nam thuc) OR (am thuc)) va dan vai cau theo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sac) OR (toc sach)) ky lang xa hoi. hieu va ((nam thuc) or (am thuc)) va dan vai cau theo".
• Adding a wildcard symbol may retrieve word variants: ((toc sac) OR (toc sach)) ky lang xa hoi. hieu va ((nam thuc) or (am thuc)) va dan vai cau theo*.