Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
dien cuc » dien tu, dieu cua, vien cac
doc sach » toc sach, nuoc sach, dac sac
va dinh » van dinh, va kinh, va tinh
va danh » va dan, va hanh, dia danh
cam luc » cam xuc, cau luc
cuc tre » duc tre, cua tre, cuu tre
hieu va » lieu va, hieu qua
vu nang » vuc nang, va nang, vu dang
nang o » nang co, nang ho, nang ro
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 (doc sach)) vu nang o hoc. hieu va cam luc ((va danh) OR (va dinh)) dien cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sach) OR (doc sach)) vu nang o hoc. hieu va cam luc ((va danh) OR (va dinh)) dien cuc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc sach) or (doc sach)) vu nang o hoc. hieu va cam luc ((va danh) OR (va dinh)) dien cuc tre".
• Adding a wildcard symbol may retrieve word variants: ((hoc sach) or (doc sach)) vu nang o hoc. hieu va cam luc ((va danh) OR (va dinh)) dien cuc tre*.