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