Search for "protoporphyrin IX" in Full Text gives 3 result(s) in Beilstein Journal of Organic Chemistry.
Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83
Beilstein J. Org. Chem. 2014, 10, 2414–2420, doi:10.3762/bjoc.10.251
Beilstein J. Org. Chem. 2008, 4, No. 53, doi:10.3762/bjoc.4.53