Q. When a journal changes its name, should I use the name of the journal when the article was published or the current name when citing an article contained in the journal?
A. Use the name of the journal when the article was published. For example,
Todd, Alexander. “Nucleic Acids and Their Role in Future Chemotherapy of Tumours and Virus Diseases.” British Medical Journal 2, no. 5151 (1959): 517–22.
If you want to signal to readers that the journal now uses a different name, mention that fact in your text or in a note—or add a bracketed clarification to your citation as follows:
Todd, Alexander. “Nucleic Acids and Their Role in Future Chemotherapy of Tumours and Virus Diseases.” British Medical Journal [now BMJ] 2, no. 5151 (1959): 517–22.