http://www.wingovernmentcontracts.com/federal-government-contracting-process-overview.htm

http://www.enco-journal.com/journal/ej42/giornale.htm

http://www.piniweb.com.br/construcao/noticias/ampliando-um-grande-projeto-83121-1.asp

http://www.miliarium.com/Licitaciones/LicitacionesLatinoamerica.asp

http://www.comprasnet.gov.br/

http://www.cgu.gov.br/Legislacao/Leis.asp

http://www.comprasnet.gov.br/main2.asp

YPFB bolivia

http://www.ypfb.gob.bo/index.php?option=com_content&view=article&id=121&Itemid=123