I showed a veterinarian friend, (recent immigrant, educated here) how to change the fluorescent lamps in his office.
He called and told me that he was having problems, they "aren't like the tube lamps".
It was a 60A19.(Edison base 60 watt incandescent)
This guy has 4 Degrees, is a well respected Doctor, but apparently none in screwing in a light bulb. [Linked Image]