Analysis of information sources in references of the Wikipedia article "Benzylpenicillin" in English language version.
Natural penicillin (PenG), penicillinase-resistant penicillin (methicillin), extended-spectrum penicillin (amoxicillin), and broad-spectrum penicillin (carbenicillin) all have the same core β-lactam ring, which is essential for antimicrobial activity.