Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
hieu va » lieu va
cac duc » cac du, cao duc, cac dac
va hanh » van hanh, va thanh, va danh
dai cuu » dai huu
x hoi » xa hoi, o hoi, x ho

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 x hoi. ((hieu va) or (hieu qua)) cac duc va hanh ((dai cuu) OR (dai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty nang x hoi. ((hieu va) OR (hieu qua)) cac duc va hanh ((dai cuu) OR (dai cua)) tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty nang x hoi. ((hieu va) or (hieu qua)) cac duc va hanh ((dai cuu) OR (dai cua)) tre*".