There are many acceptable ways to credit authors. Some of them may have their own specific way that they may wish to be identified to the public, if at all, so we encourage you to contact them directly to find out if and how they wish to be credited.
By default, an ideal way to credit authors is to take a line like the following:
Portions of this product are copyright © [year(s)] by [author(s)].
-Or-
Portions of this product were designed/developed by [author(s)].
- And place the notice it in the product's documentation, splash screen, About Box, or wherever else copyright information would normally be shown.
