Reschke, Carol; Reid, Ron; Jones, Judith; Feeney, Tom; Potter, Heather (1999). «Conserving Great Lakes Alvars»(PDF). Final Technical Report of the International Alvar Conservation Initiative. Chicago, IL.: Alvar Working Group, The Nature Conservancy. Arkivert fra originalen(PDF) 13. oktober 2008.
Reschke, Carol; Reid, Ron; Jones, Judith; Feeney, Tom; Potter, Heather (1999). «Conserving Great Lakes Alvars»(PDF). Final Technical Report of the International Alvar Conservation Initiative. Chicago, IL.: Alvar Working Group, The Nature Conservancy. Arkivert fra originalen(PDF) 13. oktober 2008.