http://listserv.okstate.edu/scripts/wa.exe?A2=ind9805&L=ed-futrs&P=1805

http://listserv.okstate.edu/

malasia 2020

http://www.idtechex.com/products/en/presentation.asp?presentationid=102

casos en km
http://www.idtechex.com/products/en/view.asp?publicationid=9

http://www.idtechex.com/pdfs/en/B4367Z4461.pdf