Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
chat duc » chat xuc, chat doc, chet duoc
cau tren » cu tren, dau tren, ca tren
va nang » van nang, da nang, cam nang
ve chat » va chat, van chat
va hanh » van hanh, va thanh, va danh
cuu tre » cua tre, cau treo
hieu ve » hieu va, hieu van
v nang » vu nang, van nang, voi nang

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ((v nang) OR (va nang)) xa hoi. hieu ve chat duc va hanh vi ((cuu tre) OR (cau tren))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ((v nang) or (va nang)) xa hoi. hieu ve chat duc va hanh vi ((cuu tre) OR (cau tren))~".
• Adding a wildcard symbol may retrieve word variants: doc sach ((v nang) or (va nang)) xa hoi. hieu ve chat duc va hanh vi ((cuu tre) OR (cau tren))*.