title: A search for porphyrin biomarkers in Nonesuch Shale and extraterrestrial samples.
mesh_terms: D005118:Extraterrestrial Environment; D013058:Mass Spectrometry; D010163:Paleontology; D011166:Porphyrins / Q000032:analysis*; D013050:Spectrometry, Fluorescence
chemical_list: D011166:Porphyrins