While the original 1964 edition is a vintage collector's item in print, digital versions (often labeled "extra quality") are available for study through various platforms: Beacon Bible Commentary, Volume 6 - The Foundry Publishing
Before the advent of quick internet searches, commentators invested years in original research. The Beacon commentators (such as William Greathouse on Revelation) wrote with a depth rarely seen in today’s "publish fast" environment. comentario biblico beacon tomo 6 pdf extra quality