A simple solution is to use the display program command dsppgm. When used properly the display program command will almost always provide the location of the original source information.
dsppgm mylib/mypgm
Typing dsppgm along with the program name and pressing Enter presents the program information screen "display 1 of 7". Pressing Enter twice takes you to the "display 3 of 7" screen which allows input of option '5=Display description'. Typing option 5 and pressing Enter presents the "module attributes" along with the name and location of the source used when creating the object.
The source information is also available for copies of the original object. That is, if a program object is duplicated (e.g. copied using crtdupobj) using dsppgm for the new copy the original source information will display.