calorie

https://dx.doi.org/10.1351/goldbook.C00784
Non-SI unit of energy. There are three differently defined calories: thermochemical calorie (cal th = 4.184 J), international steam table calorie (cal IT = 4.1868 J), 15 °C calorie (cal 15 = 4.1855 J), however only the symbol cal is usually used.
Source:
PAC, 1996, 68, 957 (Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page 964