Perhaps you should try some spelling variations:
lieu nguon » hieu nguon, dien nguon
lieu nguoi » dien nguoi, le nguoi, biet nguoi
dao nguoi » cho nguoi
tay nguoi » toc nguoi
mach hoc » cach hoc, dich hoc, anh hoc
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
tu mach » tu cach, tu manh, tu hach

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu mach hoc ((tay nguoi) or (dao nguoi)) ) or ( tu cac nuoc ((lieu nguoi) OR (lieu nguon)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu mach hoc ((tay nguoi) OR (dao nguoi)) ) OR ( tu cac nuoc ((lieu nguoi) OR (lieu nguon)) ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu mach hoc ((tay nguoi) or (dao nguoi)) ) or ( tu cac nuoc ((lieu nguoi) OR (lieu nguon)) ))*".