Please see "The Doughboys (America and the First World War) by Gay Mead (Overlook Press,Woodstock, NY, 2000). He specifically mentions the 27th on pp.149, 204, 275, 279 and 389. his bibliography and notes may lead you where you want to go. Photos 42 and 43 may be of use also.
The US intervention in North Russia is mentioned, pp. 510-513 in "The United States in the First World War, an Encyclopedia (Garland, NY, 1999).
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