|TIP: Although the 4th edition is online, you need to consult the 1975 Marcel Dekker 73 volume set in the Reference Collection as well since it covers much more content. Use the Subject Indexes in volumes 46, 47, and 73 to locate entries on twentieth century library dignitaries such as Otlet, Henri La Fontaine, Ranganathan, etc.|
TIP: Search the LIS databases for journal articles on eminent librarians profiled on this page. Remember that Library Literature Retrospective (1905-1983) might be useful.
Note: for La Fontaine and Otlet you might look outside of the LIS literature as well.