Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cao hoi » cau hoi, co hoi, cao hoc
va cam » va cham, va cac, va cai
va cao » va cac, va co, va dao
y nang » ky nang, ly nang, v nang
xuc va » duc va, tuc va, luc va
va dan » ca dan, va dao, va dau
du cuu » tu cuu
tu cua » hu cua, vu cua

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