Window:
Hans:
Oven door glass is tempered glass. Unless one of our real experts like John combo52 knows something the rest of us don't, you should be able to have tempered glass of the correct thickness cut to size.
Oven door windows of that vintage are usually pretty similar - there are two (sometimes three) pieces of glass held in a metal frame that is between the inner and outer panels of the door. Air spaces are between each piece of glass; this is what keeps the window reasonably cool.
You will need to get the outer panel off the door. On ranges of that vintage, the door is not a lift-off door, so you need to be very observant of how the door and hinges work as you're disassembling.
Once you're inside the door, you'll see how to get the glass pack (the frame holding the pieces of glass, plus the glass itself) out of the door.
Somewhere along the frame, you will usually see that it was made from one long piece of metal, and you will see how it is joined together. One common method is a couple of metal tabs in one end of the piece of metal inserted through slots in the other end, then bent over to lock the metal into its final, rectangular shape. Careful prying of these tabs will release the frame, and then you can lift out the glass.
To reassemble, you would have Donald hold the frame and glass in alignment while you put the tabs back through the slots and re-bend them. Be careful doing that, because if you break a tab, your frame is toast, and it's not a very easy part to find.
You would then put the glass pack back in the oven door where it belongs, and reassemble the door.
This is all a very generic, simplified explanation, but it has been a long, long time since I've done this. Present-day ovens have window glass that is not installed anything like the same way, so there's not much explanation of these older window systems on the Internet.