First there are two studies commonly refered to as the Lehrburger studies.  These were studies authored by Carl Lehrburger.  The studies appear to have been written for and paid for by NADS. 

Study 1 - "Diapers: Environmental Impacts and Life Style Analysis" - January 1991

Part 1
Part 2
Part 3
Part 4
Part 5
Part 6

Study 2 - "Diapers in the Waste Stream: A Review of Waste Management and Public Policy Issues" - December 1989

Part 1
Part 2
Part 3
Part 4
Part 5

These next two items are from  the Women's Environmental Network in the United Kingdom.  One is authored by them and one is commissioned by them.

Study 1 - "Preventing Nappy Waste Background and Strategy For London" - July 1996

Part 1
Part 2
Part 3

Study 2 - "A Review of Proctor and Gamble's Environmental Balances For Disposable and Reusable Nappies" - July 1991

Part 1
Part 2

The above seem to be the biggies.  The rest of the documents from the archive are listed below.  There may be some gems in here depending upon what your looking for.

"A Diaper Rash Survey Among Diaper Service Owners" - by Weiss & Associates - no date

"Acute Resipatory Effects of Diaper Emissions" - by Anderson Laboratories, Inc. - from the Archives of Environmental Health, September/October 1999

"Caring For Baby" - by William and Martha Sears - excerpt from "The Baby Book" - 1993 (chapter of cloth diapers)

"Cloth or Disposable Diapers: The Consumer's Choice" - by The New York State Consumer Protection Board - no date

"Diapering Alternatives: A Complete Guide For Parents" - by Dale Martin, from Parenting Unlimited, 1987.

"Disposable Diapers: Potential Health Hazards?" - by Cathy Allison, Sacramento Parent Magazine, March 2000

"Energy and Water Consumption ...." - by Gainer & Associates, no date

"Influencing Policy on Diapering: Not For Babies Only" - by Primomo and Greenstreet - Journal of Perinatology, 1993