1. Caldwell, C.K.: How many primes are there? In: The Prime Pages [2].
http://primes.utm.edu/howmany.html
. Accessed 15 Oct 2016
2. Caldwell, C.K. (ed.): The Prime Pages (2016).
http://primes.utm.edu
. Accessed 15 Oct 2016
3. Chmielewski, L.J., Orłowski, A.: Hough transform for lines with slope defined by a pair of co-primes. Mach. Graph. Vis. 22(1/4), 17–25 (2013). Open access:
http://mgv.wzim.sggw.pl/MGV22.html
4. Lecture Notes in Computer Science;LJ Chmielewski,2016
5. Chmielewski, L.J., Orłowski, A.: Prime numbers in the Ulam square (2016).
http://www.lchmiel.pl/primes
. Accessed 14 Oct 2016