To P. N. Isakov, 13 January 1891. Petersburg.

A brief, formal note written from Petersburg on 13 January 1891 to Pyotr Nikolayevich Isakov. Chekhov apologizes for returning a "Bibliographical Sheet" (Bibliograficheskii listok) past the deadline Isakov had set, explaining that supplying full and accurate information required tracking down preliminary references, which took longer than expected.

The letter gives no further detail about the nature of the bibliographical item in question or the occasion for the request. Its tone – formal address ("Much-esteemed Pyotr Nikolayevich") and a closing assurance of respect and devotion rather than the joking, familiar register Chekhov used with close friends – suggests a correspondent outside his inner circle, consistent with the brief, business-like character of the note.