Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
vuc nang » vu nang, chuc nang, van nang
cuc nang » chuc nang, cuu nang, cua nang
cua tre » cua te, cuu tre, cua triet
va cam » va cham, va cao, va cai
luc va » duc va, tuc va, loc va
va dan » ca dan, va dao, va dau
dan di » danh di, dan da, dan de
di cua » dai cua, doi cua, de cua
o hoi » co hoi, o hoc, o hai

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