The second author's name is Mischke, not Mitchell. You can find more information about the book and supplements at the publisher's website (McGraw-Hill):
for the book i've got, it says shigley and MITCHELL (specifically, Larry D. Mitchell), plain as day right on the binder.......it's the 4th edition put out in 1983. looked at the site but it's not applicable to mine......too old.......thanks
You could try contacting the authors for a lead if they're still around. Shigley used to have a chair at the University of Michigan but I'm thinking he may have passed away. As to Mitchell, I have no idea.