Walter is trying to find some of his begonias to reestablish his breeding program. There are more, but this is the starting list (he may have found some by now):
Johnny B. Goode
Mack the Knife
Let us know how your search goes. As new begonia hybrids are created each year, I bet a lot of oldies are lost except the keepers that appeals to a wider audience such as Lucerna, Sophie, Irene, etc. Most folks are going to weed out the plain green ones and poor performers (maybe they are great looking but if the genes are weak it may be herculean to keep them alive).