Proletarian Esperanto movement: early history to 1937

It's rather difficult to find information in English about the proletarian Esperanto movement, which peaked between the two world wars. But here is a series of essays by David Poulson:

What About the Workers? Part One: Pioneers
The workers' Esperanto movement, 1905-1914
Nov 20, 1998 - David Poulson

What About the Workers? Part 2: "Neutrality, Out!"
A brief biography of Eugene Adam ("Lanti") and the foundation of S.A.T.
Nov 27, 1998 - David Poulson

What About the Workers? Part 3: The Formation of S.A.T.
How Sennacieca Asocio Tutmonda was begun.
Dec 11, 1998 - David Poulson

What About the Workers? Part 4
Eugene Adam announces his own suicide. Prematurely!
Dec 18, 1998 - David Poulson

What About the Workers? Conclusion
SAT resists Communist takeover attempt.
Jan 8, 1999 - David Poulson

Aside from the first essay, this is mostly the story of Eugène Lanti and the Sennacieca Asocio Tutmonda [SAT = World Anationalist Association].  Poulson ends his story in 1937 with Stalin's liquidation of the Soviet Esperantists, whose leader Ernest Drezen was himself guilty of dictatorial behavior and the attempted disruption of SAT. The adaptation of Soviet Esperantists to Stalinism did not save them. Soviet (specifically Drezen's) behavior mentioned herein pertains to and was characteristic of the "Third Period" of the Third International. To what extent Drezen's behavior was self-motivated or the result of a process of corruption by the Stalinist system should be examined. In any event, these essays are only sketches of the relevant history.