Perhaps you should try some spelling variations:
van thinh » van thanh, van chinh, van minh
hieu va » lieu va, hieu qua
nam qua » nam quan, nam cua, nam mua
cua tre » cua te, cuu tre, cua triet
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky
va nam » van nam, ha nam, va nay
vi cua » vai cua, di cua
x hoi » xa hoi, x ho, 5 hoi
o hoi » co hoi, o hoc, o hai

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 ky nang ((x hoi) OR (o hoi)). hieu va nam qua ((lap trinh) or (van thinh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky nang ((x hoi) OR (o hoi)). hieu va nam qua ((lap trinh) OR (van thinh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky nang ((x hoi) OR (o hoi)). hieu va nam qua ((lap trinh) or (van thinh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sac ky nang ((x hoi) OR (o hoi)). hieu va nam qua ((lap trinh) or (van thinh)) vi cua tre*.