Little owl nest box design info

Hi, I've been researching little owls for part of my uni dissertation and I've hit some issues when it comes to talking about nest box type in my discussion- the dataset I'm using mentions lots of nest box types that I can't find any info on online. I also don't own the BTO box guide, so even ones that come from there I don't know the designs of. I'm only going to cover the designs that come up most in the datset, which will be the following-

For 'hole' type nest boxes: 'BTO guide large hole', 'BTO guide barn owl', 'RS Little Owl Box' or 'RS Ammunition box'

For 'tunnel' type nest boxes: 'RD/RED None Guide Little Owl (Special)'

For 'other' type nest boxes: 'Barn Owl Mk2', 'Little Owl Box Hawk & Owl Trust Design', 'Little Owl Box Internal Baffle front opening' (this one sounds similar to the Bob Shepherd design which I have been able to find info on)

If anyone knows anything about these box types or can direct me to somewhere where I could find more info on them I'd really appreciate it :)