Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu ve » hieu va, hieu van
cac luc » cau luc, coc luc, cac nuoc
lua tre » cua tre, luy tre, dua tren
y nang » ky nang, ly nang, v nang
ve cac » va cac, vien cac
luc va » duc va, tuc va, loc va
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
vi lua » vi luu
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: ((te sach) OR (toc sach)) y nang x hoi. hieu ve cac luc va dan vi lua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) y nang x hoi. hieu ve cac luc va dan vi lua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) y nang x hoi. hieu ve cac luc va dan vi lua tre*.