Spengler LeECG Serie Manuel De L'utilisateur page 166

V3R+V4R+V5R Right-sided Chest Leads

C3R: on the right side of chest, opposite to the C3 electrode position.
C4R: on the right side of chest, opposite to the C4 electrode position.
C5R: on the right side of chest, opposite to the C5 electrode position.
V7+V8+V9 Posterior Chest Leads

C7: on the left posterior axillary line, at the same level as C4~C6
C8: on the left scapular line, at the same level as C4~C7
C9: on the left paraspinal border, at the same level as C4~C8
11-10