Probably in a Spanish, German and UK book. Those are the places that have had them long enough to be considered.
My purpose for translating them from Spain, Argentinian and Irish was to prevent a lot of deviations based on what birds here have become. IMHO it would behoove us to strive to get our birds to that point.
I joined a couple Aussie groups a few years ago because I did find people there with Blacks.
I had Welsummers a few years ago and their eggs were quite dark so I got addicted. I wanted to find what other breeds laid dark eggs so I could raise them. Welsummers are fairly common and Marans are very common so I wasn't interested since I have an innate need to be different. I wanted something rare, unusual, obscure AND that laid a dark egg. I discovered Penedesencas and since I eat the extra boys, I was only interested in the DP Blacks.
After about 6 months of searching I stumbled on someone that had just hatched some chicks and bought them.
I was instantly enamored.
They are VERY hardy(take whatever you throw at them), wild(predator proof), unique(only bird with white earlobes that lays a brown egg and a carnation comb), flavor is one of the worlds most sought after chicken meat ('Fira del Gall' - 'Fair of the Rooster')
Oh, and did I say they laid a lot of big pretty eggs?
Too bad the gene pool is so small here.