https://doi.org/10.1351/goldbook.M03935
Non-SI unit of @P04686@. \[1^{\prime} = (1/60)^{\,\unicode{x26ac}} = 2.908\ 882\,...\,\times 10^{-4}\text{rad}\]
Sources:
Green Book, 2nd ed., p. 113 [Terms] [Book]
PAC, 1996, 68, 957. (Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page 981 [Terms] [Paper]