Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hang dau » hang va, hang tai
va triet » va thiet, va trien, ve triet
ky dang » ky danh
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
va hang » van hang, va nang, va lang
tuc va » thuc va, truc va, tuc xa
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: toc sach ((ky dang) OR (ky nang)) xa hoi. hieu va cac tuc va hang dau ((va triet) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ky dang) OR (ky nang)) xa hoi. hieu va cac tuc va hang dau ((va triet) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ky dang) OR (ky nang)) xa hoi. hieu va cac tuc va hang dau ((va triet) or (cua te))".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ky dang) OR (ky nang)) xa hoi. hieu va cac tuc va hang dau ((va triet) or (cua te))*.