The Heilbroner Baseball Bureau was established in 1909 and collected data and statistical info of professional players. Much of this information was the foundation of the Heilbroner Blue Books, which were published and marketed primarily to baseball insiders during the early-mid 20th century. Mostly consisting of 3 x 5 index cards with abbreviated stat / notations and questionnaires, which were larger and more detailed. Most of the questionnaires came from Karl Wingler, a dedicated Heilbroner employee who assembled thousands of these questionnaires (most filled out in the player's hand). The 3 x 5's were sold (many decades ago) to SABR co-founder Ray Nemec who used them as the basis for his player profiles / and lifetime records. Nemec passed away a few years ago and the index cards were broken down
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