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