Of a source of @[email protected] \(I\) in an element of solid @[email protected] \(\text{d}\varOmega\) is given by \(\text{d}\varPhi = I\ \text{d}\varOmega\).
Sources: Green Book, 2nd ed., p. 72 [Terms] [Book] PAC, 1996, 68, 957. (Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page 979 [Terms] [Paper]