Δ (delta), Λ (lambda)

https://doi.org/10.1351/goldbook.D01511
Designations of @S05984@ of tris(didentate) metal complexes and other octahedral complexes.
See:
helicity
Sources:
PAC, 1996, 68, 2193. (Basic terminology of stereochemistry (IUPAC Recommendations 1996)) on page 2205 [Terms] [Paper]
Red Book, 3rd ed., p. 184 [Terms] [Book]