Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
va danh » va dinh, va dan, dia danh
va hanh » van hanh, va thanh, ban hanh
dau sua » dai sua, dau cua, dau su
sach ly » sach y, sach lo, sach ty
van dau » van dao, phan dau
ly nang » ky nang, ly hang, ly vang
vi cua » vai cua, di cua
cua tu » cua tuc, cua su, cua cu
5 hoi » o hoi

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 ly nang ((5 hoi) or (xa hoi)). hieu van dau sua ((va hanh) OR (va danh)) vi cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ly nang ((5 hoi) OR (xa hoi)). hieu van dau sua ((va hanh) OR (va danh)) vi cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ly nang ((5 hoi) or (xa hoi)). hieu van dau sua ((va hanh) OR (va danh)) vi cua tu".
• Adding a wildcard symbol may retrieve word variants: toc sach ly nang ((5 hoi) or (xa hoi)). hieu van dau sua ((va hanh) OR (va danh)) vi cua tu*.