The problem with using aversives is that the dog eventually becomes immune to it. Then, you have to use a higher frequency and the dog will stop temporarily. Then, the dog once again develops immunity and you have to keep increasing the frequency of the aversive until it eventually reaches a physically dangerous level. On top of that, aversives often produce aggression and fear. I would never use neither shock nor citronella collar on my dogs. Instead of DON'T BARK OR I'LL SHOCK YOU (which creates fear and other mentally unhealthy stuff), try When the doorbell rings, look at me for treats. You can gradually shape this by doing a Sit-Stay or Sit-Watch Me when a person walks through the door. Have your dog on the leash and have a friend there to help you. Sit on a chair in front of the door and command a Sit-Stay from your dog. Have your friend knock on the door and command a Watch Me at the exact same time. If she doesn't perform because the urge to bark is stronger than the urge for treats, go back a few steps and use extremely high value treats. I personally haven't done this, but a trainer I know uses this technique. You can even do this by yourself by knocking on the wall to imitate the sound of the door. I know this always fools my dogs Eventually, you can go up to the actual doorbell. Hope this helps.