Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
cao xuc » cam xuc, cao duc, cao suc
tai cua » thai cua, tai cuc, tri cua
ly nang » ky nang, ly hang, ly vang
xuc van » duc van, luc van, vuc van
hieu va » lieu va, hieu qua
co hoi » co hoc
va cao » va cac, va co, va dao
cua tu » cua tuc, cua su, cua cu

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