Googled it :-) Helsing attributed it to Jelliffe  (1978)

War on Want attributed it to ref #13 in The Baby Killer by Muller,1974, 
however the ref page isn't on the web site, just the body of the pamphlet. I 
did a quick look in CBI, but can't come up with pamphlet.  Maybe Virgina has 
that one.  Pat in SNJ 

             ***********************************************

Archives: http://community.lsoft.com/archives/LACTNET.html
To reach list owners: [log in to unmask]
Mail all list management commands to: [log in to unmask]
COMMANDS:
1. To temporarily stop your subscription write in the body of an email: set lactnet nomail
2. To start it again: set lactnet mail
3. To unsubscribe: unsubscribe lactnet
4. To get a comprehensive list of rules and directions: get lactnet welcome