Graybiel, A. (1952). Electrocardiography in practice. Saunders.
Lua i Stíl Chicago (17ú heag.)Graybiel, Ashton. Electrocardiography in Practice. Philadelphia: Saunders, 1952.
Lua MLA (9ú heag.)Graybiel, Ashton. Electrocardiography in Practice. Saunders, 1952.
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