Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
ly nang » ky nang, ly hang, ly vang
sach ly » sach y, sach lo, sach ty
dau sua » dai sua, dau cua, dau xua
va hanh » van hanh, va thanh, va danh
dau su » dau tu, dan su, da su
vi cua » vai cua, di cua
cua te » cua tu
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) OR (dau su)) va hanh vi cua te~.
• 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) OR (dau su)) va hanh vi cua te.
• 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) OR (dau su)) va hanh vi cua te".
• Adding a wildcard symbol may retrieve word variants: toc sach ly nang ((5 hoi) or (xa hoi)). hieu van ((dau sua) OR (dau su)) va hanh vi cua te*.