RT Journal Article SR Electronic T1 Spontaneous oral hematoma diagnosed as angina bullosa hemorrhagica JF Cleveland Clinic Journal of Medicine JO Cleve Clin J Med FD Cleveland Clinic SP 615 OP 616 DO 10.3949/ccjm.89a.22040 VO 89 IS 11 A1 Takeshi Onda A1 Kamichika Hayashi A1 Akira Katakura A1 Masayuki Takano YR 2022 UL http://www.ccjm.org/content/89/11/615.abstract AB