Perhaps you should try some spelling variations:
hieu cua » hieu qua, dieu cua, bieu cua
may nang » may nong, ky nang, cam nang
va nang » van nang, da nang, cam nang
va hang » van hang, va lang, va hanh
cac xuc » cam xuc, cac nuoc, chat xuc
so sach » so sanh, bo sach, co sach
v nang » vu nang, van nang, voi nang
di cua » dai cua, doi cua, de cua
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: so sach ((may nang) or (v nang)) x hoi. hieu cua cac xuc ((va hang) OR (va nang)) di cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((may nang) OR (v nang)) x hoi. hieu cua cac xuc ((va hang) OR (va nang)) di cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((may nang) or (v nang)) x hoi. hieu cua cac xuc ((va hang) OR (va nang)) di cua vat".
• Adding a wildcard symbol may retrieve word variants: so sach ((may nang) or (v nang)) x hoi. hieu cua cac xuc ((va hang) OR (va nang)) di cua vat*.