‘Upside-down’ shelf brackets

Can’t think of a better way of describing this but I’m looking for shelf brackets that fix to the wall behind / above the shelf itself, rather than having it sit underneath.

Essentially something like this or this... though I’m not particularly pushed on the specific style or design.

Does anyone know of somewhere in Dublin that might have options like these? Anywhere I’ve looked so far just has your bog-standard bracket type while online options would cost a fair whack once delivery is considered.

I’ll be using the shelves for books so need it to be strong enough - which is why I’m also looking passed floating shelves (Which, in my experience at least, tend to be a bit weaker).

Thanks for any help!