Gaya APA
HELFANT, R, H. (1980).
Bellet's essentials of cardiac arrhythmias (2rd ed.).
Philadelphia:
W.B. Saunders Company.
Gaya MLA
HELFANT, Richard, H..
"Bellet's essentials of cardiac arrhythmias".
2rd ed.
Philadelphia:
W.B. Saunders Company,
1980.
Buku.