நிறைவெண் (கணிதம்): திருத்தங்களுக்கு இடையிலான வேறுபாடு

* David Moews: [http://djm.cc/amicable.html Perfect, amicable and sociable numbers]

* [http://www-history.mcs.st-andrews.ac.uk/HistTopics/Perfect_numbers.html Perfect numbers - History and Theory]

* [http://www.oddperfect.org OddPerfect.org] A projected distributed computing project to search for odd perfect numbers

* [http://www.mersenne.org/(GIMPS) Great Internet Mersenne Prime Search]

* [http://mathforum.org/dr.math/faq/faq.perfect.html Perfect Numbers], Math forum at Drexel