@MISC{BASEL_1.MIZ,
  AUTHOR = {Korni{\l}owicz, Artur and P\k{a}k, Karol},
  TITLE = {Basel Problem -- Preliminaries},
  DAY = {27},
  MONTH = {June},
  YEAR = {2017},
  ADDRESS1 = {Institute of Informatics\\University of Bia{\l}ystok\\Cio{\l}kowskiego 1M, 15-245 Bia{\l}ystok\\Poland},
  ADDRESS2 = {Institute of Informatics\\University of Bia{\l}ystok\\Cio{\l}kowskiego 1M, 15-245 Bia{\l}ystok\\Poland},
  SECTION1 = {Preliminaries},
  SECTION2 = {Limits of sequences $\frac{an+b}{cn+d}$},
  SECTION3 = {Trigonometry},
  SECTION4 = {Some special functions and sequences},
  SUMMARY = {In the article we formalize in the Mizar system
  \cite{Mizar-State-2015} preliminary facts needed to prove
  the Basel problem. Facts that are independent from the notion
  of structure are included here.},}
