1. Petroporphyrins of gilsonite;Alturki,1972
2. Mass spectrometry of porphyrins, II. Characterization of petroporphyrins;Baker;J. Am. Chem. Soc.,1967
3. Separation and structure of petroporphyrins;Barwise,1980
4. Evidence for isomerism in fossil porphyrins of 420–504 molecular weight (desoxophyll-erythrin series);Blumer;An. Acad. Bras. Cienc.,1974
5. High molecular weight fossil porphyrins: evidence for monomeric and dimeric tetrapyrroles of about 1100 molecular weight;Blumer;J. Inst. Petrol.,1970