RT Journal Article SR Electronic T1 Two dimensional speckle tracking echocardiography: basic principles JF Heart JO Heart FD BMJ Publishing Group Ltd and British Cardiovascular Society SP 716 OP 722 DO 10.1136/hrt.2007.141002 VO 96 IS 9 A1 Hermann Blessberger A1 Thomas Binder YR 2010 UL http://heart.bmj.com/content/96/9/716.abstract AB