Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, hieu ve
nam thuc » nam thuoc, am thuc, nam thu
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, nang ma
xa hanh » xa thanh, xa khanh, va hanh
hanh va » hang va, hanh vi
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
nam tu » nam thu
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: tu sach y nang xa hoi. ((hieu van) or (lieu va)) ((nam tu) OR (nam thuc)) xa hanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang xa hoi. ((hieu van) OR (lieu va)) ((nam tu) OR (nam thuc)) xa hanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang xa hoi. ((hieu van) or (lieu va)) ((nam tu) OR (nam thuc)) xa hanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang xa hoi. ((hieu van) or (lieu va)) ((nam tu) OR (nam thuc)) xa hanh va cua tre*.