Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
vuc nang » cuc nang, vu nang, chuc nang
sach vuc » sach duoc, sach nuoc, sach truc
nang co » nang cao, nang doc, nang noi
cua tre » cuu tre, cua triet, dua tren
dan di » danh di, dan da, dan de
cua te » cua tu
va dan » ca dan, va dao, va dau
va cam » va cham, va cao, va cai
co hoi » co hoc, co loi

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