Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
toc sach » hoc sach, doc sach, nuoc sach
cua tre » cua te, cuu tre, cua triet
vu nang » vuc nang, va nang, vu dang
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
va cam » va cham, va cao, va cai
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 (thuoc sach)) vu nang x 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) OR (thuoc sach)) vu nang x 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) OR (thuoc sach)) vu nang x hoi. hieu ((va cam) or (va cac)) luc va dan di cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (thuoc sach)) vu nang x hoi. hieu ((va cam) or (va cac)) luc va dan di cua tre*.