It was written by Drew Daniels, who was Applications Engineer at JBL Professional from 1984 to 1989. The above articles are a part of the Lansing Heritage site. Another modest attempt. Madisound is a great source of drivers and other parts. Request a copy of their catalog and you will get a thick sheaf containing complete specs on a lot of drivers.
Passive crossovers are a real bear to design.
They have a large archive of speaker related downloadable software . Descriptions are in catalog.txt . Check out Box Plot. Parts Express . Get their catalog.