Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu va » lieu va, hieu qua
vu nang » vuc nang, va nang, vu dang
cam loc » cam lo
cua tre » cua te, cuu tre, cua triet
v nang » va nang, van nang, voi nang
va cam » va cham, va cac, va cao
loc va » hoc va, luc 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
x hoi » o hoi, x ho, 5 hoi

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