Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
dien cuc » dien tu, dieu cua, vien cac
va dinh » van dinh, va kinh, va tinh
cam luc » cam xuc, cau luc
hieu va » lieu va, hieu qua
cuc tre » duc tre, cua tre, cuu tre
vu nang » vuc nang, va nang, vu dang
nang o » nang co, nang ho, nang ro
va dan » ca dan, va dao, va dau
va cam » va cham, va cac, va cao
o hoc » co hoc, mo hoc, so hoc

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((hoc sach) or (dac sac)) vu nang o hoc. hieu va cam luc ((va dan) or (va dinh)) dien cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sach) OR (dac sac)) vu nang o hoc. hieu va cam luc ((va dan) OR (va dinh)) dien cuc tre.
• Adding a wildcard symbol may retrieve word variants: ((hoc sach) or (dac sac)) vu nang o hoc. hieu va cam luc ((va dan) or (va dinh)) dien cuc tre*.