Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cau tren » cu tren, dau tren, ca tren
va nang » van nang, da nang, cam nang
hieu va » lieu va, hieu qua
cao luc » bao luc, cao duc, cao suc
va danh » va dinh, va dan, va hanh
danh di » danh du, xanh di, danh dien
v nang » vu nang, van nang, voi nang
va cao » va cac, va co, va dao
luc va » duc va, tuc va, loc va
di cau » da cau, diem cau

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 (va nang)) xa hoi. hieu va cao luc va danh di cau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((v nang) OR (va nang)) xa hoi. hieu va cao luc va danh di cau tren".
• Adding a wildcard symbol may retrieve word variants: toc sach ((v nang) OR (va nang)) xa hoi. hieu va cao luc va danh di cau tren*.