How to Cite
By now, everyone knows that 2019 has been dedicated to the International Year of the Periodic Table of the chemical elements (IYPT) by UNESCO. At the very least, this is true for the chemical community and science teachers and popularizers at large. On many occasions during this year, historical accounts have been provided by specialists and profane alike. The year 2019 was chosen precisely because it corresponds to the 150th anniversary of the first publication of a classification of the then known elements by Dmitrii Ivanovitch Mendeleev (transcribed from the Russian as Dmítriy Ivánovich Mendeléyev), a classification he ended up calling a periodic system when publishing it.