A Conversation with Craig Bohmler, composer of GUNMETAL BLUES, playing now at A/C Theatre Company [online]. 2018-05-18 [cit. 2018-11-03]. Dostupné online.
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Quick Facts. Riders of the Purple Sage [online]. [cit. 2018-11-03]. Dostupné online. (anglicky)
GRIFFEL, Margaret Ross. Operas in English : a dictionary. Revidované. vyd. Lanham, Md.: Scarecrow Press, 2013. 2 díly (xxvi, 984 stran) s. ISBN9780810882720, ISBN0810882728. OCLC793224284 Kapitola The Achilles Heel, s. 3.