Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
ban hanh » ban hang
va triet » va thiet, va trien, ve triet
hieu va » lieu va, hieu qua
cau duc » cao duc, cau luc, chu duc
ty nang » ty xang, ty hang, ly nang
dien va » dien hoa
va cau » van cau, va cac, va dau
o hoi » co hoi, o hoc, o hai

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 ((ty nang) OR (ky nang)) o hoi. hieu va cau duc ((ban hanh) or (gia thanh)) dien va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ty nang) OR (ky nang)) o hoi. hieu va cau duc ((ban hanh) OR (gia thanh)) dien va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ty nang) OR (ky nang)) o hoi. hieu va cau duc ((ban hanh) or (gia thanh)) dien va triet".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ty nang) OR (ky nang)) o hoi. hieu va cau duc ((ban hanh) or (gia thanh)) dien va triet*.