Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hoc cac » hoc cao
hieu va » lieu va, hieu qua
va danh » va dinh, va dan, va hanh
hai cua » thai cua, hoi cua, lai cua
va cam » va cham, va cac, va cao
xuc va » duc va, tuc va, luc va
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) or (hoc cac)) ky nang x hoi. hieu va cam xuc va danh ((hai cua) OR (dai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc cac)) ky nang x hoi. hieu va cam xuc va danh ((hai cua) OR (dai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (hoc cac)) ky nang x hoi. hieu va cam xuc va danh ((hai cua) OR (dai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (hoc cac)) ky nang x hoi. hieu va cam xuc va danh ((hai cua) OR (dai cua)) tre*.