Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dua tren » dung tren
cau treo » cau theo, cau tren, cau triet
va dinh » van dinh, va kinh, va tinh
hieu va » lieu va, hieu qua
dinh di » dinh du, dinh vi, danh di
cac luc » cau luc, coc luc, cac nuoc
luc va » duc va, tuc va, loc va
v nang » va nang, vu nang, van nang
o hoi » co hoi, o hoc, o hai

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 (van dong)) o hoi. hieu va cac luc va dinh di ((dua tren) or (cau treo))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((v nang) OR (van dong)) o hoi. hieu va cac luc va dinh di ((dua tren) OR (cau treo)).
• Adding a wildcard symbol may retrieve word variants: toc sach ((v nang) or (van dong)) o hoi. hieu va cac luc va dinh di ((dua tren) or (cau treo))*.