Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thanh le » thinh le, thanh ve, thanh de
luoc van » luoc can, luoc va, luc van
va triet » va thiet, va trien, ve triet
sang ma » tang ma, nang ma, sang tao
sach ky » sac ky, sach y, sach ty
xuc van » duc van, luc van, vuc van
nang xa » nang x, lang xa, nang ma
qua cac » cua cac
le va » le van, te va, ly va

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 ((nang xa) or (sang ma)) hoi. hieu qua cac ((xuc van) or (luoc van)) thanh le va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((nang xa) OR (sang ma)) hoi. hieu qua cac ((xuc van) OR (luoc van)) thanh le va triet.
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((nang xa) or (sang ma)) hoi. hieu qua cac ((xuc van) or (luoc van)) thanh le va triet*.