Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
va thanh » gia thanh, ban thanh, le thanh
su sach » so sach, vu sach
va tinh » may tinh
nam tuc » nam thuc, nam truc, nam tu
ly nang » ky nang, ly hang, ly vang
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, v nang, may nang
va cua » va chua, via cua, ca 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 ((y nang) or (ly nang)) xa hoi. hieu van nam tuc ((va thanh) OR (va tinh)) va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((y nang) OR (ly nang)) xa hoi. hieu van nam tuc ((va thanh) OR (va tinh)) va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((y nang) or (ly nang)) xa hoi. hieu van nam tuc ((va thanh) OR (va tinh)) va cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((y nang) or (ly nang)) xa hoi. hieu van nam tuc ((va thanh) OR (va tinh)) va cua tre*.