RT Journal Article SR Electronic T1 ‘Inverse Double Bubble’ sign for an effective adductor canal block: a novel approach for the ultrasound confirmation of being on the right site JF Regional Anesthesia & Pain Medicine JO Reg Anesth Pain Med FD BMJ Publishing Group Ltd SP 527 OP 528 DO 10.1136/rapm-2018-100022 VO 44 IS 4 A1 Pierfrancesco Fusco A1 Stefano Di Carlo A1 Paolo Scimia A1 Emiliano Petrucci A1 Giulia Degan A1 Franco Marinangeli YR 2019 UL http://rapm.bmj.com/content/44/4/527.abstract AB