Narrow question: Did Publ. Math. Institute Hung. (Publications of the Mathematical Institute of the Hungarian Academy of Sciences) change its name? I am finalizing the bibliography of an article in progress that refers to an article that supposedly appeared in Publ. Math. Institute Hung. (see e.g. https://math.stackexchange.com/questions/3535217/in-how-many-ways-can-a-permutation-cycle-be-decomposed-as-a-product-of-transposi), but my go-to webpage for official journal abbreviations, https://mathscinet.ams.org/msnhtml/serials.pdf, appears to list no such journal. Perhaps it's now Acta Math. Hungar. or Period. Math. Hungar. or Studia Sci. Math. Hungar.?

Broader question: What is the best resource for investigating such questions? When a journal changes its name, how is a working mathematician to know?