The Polish government sent a note (ultimatum) to the government of Lithuania, in which it demanded the immediate establishment of diplomatic relations (text of the note presented by the Polish envoy in Estonia (Wacław Przesmycki) Lithuanian envoy to Estonia (Bronius Dailidė): 17/3/1938, Information provided by Poland.
The Lithuanian government notified the Polish government of the acceptance of the terms of the ultimatum and agreed to establish diplomatic relations. The date of the Lithuanian note, handed to the Polish envoy W. Przesmycki, is the date of establishment of diplomatic relations between Poland and Lithuania: 19/3/1938, Information provided by Poland.
A note of the Polish Minister of Foreign Affairs (Krzysztof Skubiszewski) with a proposal to resume diplomatic relations: 28/8/1991, Information provided by Poland.
An approving note from the Lithuanian Minister of Foreign Affairs (AlgirdasSaudargas). The date of its receipt at the Ministry of Foreign Affairs in Warsaw marked the resumption of diplomatic relations: 2/9/1991, Information provided by Poland.