Perhaps you should try some spelling variations:
cau treo » cau theo, cau tren, cau triet
thanh di » thanh doi, thanh de, thanh do
va thanh » gia thanh, ban thanh, va tinh
cac duc » cac du, cac dac, cac nuoc
cao duc » dao duc, cao suc, giao duc
su sach » so sach, vu sach
hieu ve » hieu va, hieu van
y nang » ky nang, ly nang, may nang
v nang » va nang, vu nang, van nang
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: su sach ((y nang) or (v nang)) cau hoi. hieu ve ((cac duc) OR (cao duc)) va thanh di cau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((y nang) OR (v nang)) cau hoi. hieu ve ((cac duc) OR (cao duc)) va thanh di cau treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((y nang) or (v nang)) cau hoi. hieu ve ((cac duc) OR (cao duc)) va thanh di cau treo".
• Adding a wildcard symbol may retrieve word variants: su sach ((y nang) or (v nang)) cau hoi. hieu ve ((cac duc) OR (cao duc)) va thanh di cau treo*.