Perhaps you should try some spelling variations:
nam thuoc » nam thu, nha thuoc, cay thuoc
hieu van » hieu va, thien van, lieu va
nam thuc » am thuc, nam thu, nam tu
dan hanh » dang hanh, dan khanh, dan thanh
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) OR (nam thuoc)) 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) OR (nam thuoc)) 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) OR (nam thuoc)) 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) OR (nam thuoc)) dan hanh vi cua tre*.