http://cseweb.ucsd.edu/~smeiklejohn/files/ndss14.pdf
http://research.microsoft.com/pubs/156072/bitcoin.pdf
http://cseweb.ucsd.edu/~smeiklejohn/files/imc13.pdf
http://www.cs.huji.ac.il/~avivz/pubs/13/btc_scalability_full.pdf
https://bitcoil.co.il/BitcoinX.pdf
https://cs.umd.edu/~amiller/mix.pdf
http://primecoin.org/static/primecoin-paper.pdf
http://invictus-innovations.com/s/MomentumProofOfWork.pdf
http://www.bitfreak.info/files/pp2p-ccmbc-rev1.pdf
http://cseweb.ucsd.edu/~smeiklejohn/files/imc13.pdf
http://www.macroriskadvisors.com/layout/pdf/bitcoin%20primer%20BTC.pdf
http://www.cs.technion.ac.il/~idddo/CoA.pdf