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