Perhaps you should try some spelling variations:
van nang » van quang, van ban, van dong
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
hoa lang » hoa dan, hoa van
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
va lang » va nang
cua tre » cua te, cuu tre, cua triet
v nang » va nang, vu nang, voi nang
vi cua » vai cua, di cua

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 ((v nang) or (van nang)) xa hoi. hieu va cac nuoc ((va lang) OR (hoa lang)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((v nang) OR (van nang)) xa hoi. hieu va cac nuoc ((va lang) OR (hoa lang)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((v nang) or (van nang)) xa hoi. hieu va cac nuoc ((va lang) OR (hoa lang)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((v nang) or (van nang)) xa hoi. hieu va cac nuoc ((va lang) OR (hoa lang)) vi cua tre*.