Here are links to research papers. These were listed in the Princeton University cryptocurrency course:
https://ws680.nist.gov/publication/get_pdf.cfm?pub_id=910977
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.472.9475&rep=rep1&type=pdf
http://www.hashcash.org/papers/hashcash.pdf
https://lamport.azurewebsites.net/pubs/paxos-simple.pdf
https://unglueit-files.s3.amazonaws.com/ebf/05db7df4f31840f0a873d6ea14dcc28d.pdf
https://fc13.ifca.ai/proc/1-2.pdf
https://cs.jhu.edu/~sdoshi/crypto/papers/shamirturing.pdf
https://users.encs.concordia.ca/~clark/papers/2015_ccs.pdf
https://allquantor.at/blockchainbib/pdf/taylor2013bitcoin.pdf
http://www.allied-control.com/publications/Analysis_of_Large-Scale_Bitcoin_Mining_Operations.pdf
http://www.jbonneau.com/doc/BMCNKF15-IEEESP-bitcoin.pdf
https://www.cs.cornell.edu/~ie53/publications/btcProcFC.pdf
https://www.econinfosec.org/archive/weis2013/papers/KrollDaveyFeltenWEIS2013.pdf
https://cseweb.ucsd.edu/~smeiklejohn/files/imc13.pdf
https://www.mercatus.org/system/files/Brito_BitcoinPrimer.pdf
https://svn.torproject.org/svn/projects/design-paper/tor-design.pdf
http://antoanthongtin.vn/Portals/0/UploadImages/kiennt2/Sach/Sach-CSDL4/D039.pdf
https://www.cs.ru.nl/~jhh/pub/secsem/chaum1985bigbrother.pdf
https://www.dfs.ny.gov/legal/regulations/adoptions/dfsp200t.pdf
https://www.tarsnap.com/scrypt/scrypt.pdf
http://www.std.org/~msm/common/memorybound.pdf
http://hashcash.org/papers/cuckoo.pdf
https://eprint.iacr.org/2013/784.pdf
http://www.dartmouth.edu/~ericz/predictionmarkets.pdf
https://mason.gmu.edu/~rhanson/PromisePredMkt.pdf
https://blockstream.com/sidechains.pdf
http://randomwalker.info/publications/namespaces.pdf
http://blockchainlab.com/pdf/Ethereum_white_paper-a_next_generation_smart_contract_and_decentralized_application_platform-vitalik-buterin.pdf
https://eprint.iacr.org/2015/702.pdf
https://ws680.nist.gov/publication/get_pdf.cfm?pub_id=910977
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.472.9475&rep=rep1&type=pdf
http://www.hashcash.org/papers/hashcash.pdf
https://lamport.azurewebsites.net/pubs/paxos-simple.pdf
https://unglueit-files.s3.amazonaws.com/ebf/05db7df4f31840f0a873d6ea14dcc28d.pdf
https://fc13.ifca.ai/proc/1-2.pdf
https://cs.jhu.edu/~sdoshi/crypto/papers/shamirturing.pdf
https://users.encs.concordia.ca/~clark/papers/2015_ccs.pdf
https://allquantor.at/blockchainbib/pdf/taylor2013bitcoin.pdf
http://www.allied-control.com/publications/Analysis_of_Large-Scale_Bitcoin_Mining_Operations.pdf
http://www.jbonneau.com/doc/BMCNKF15-IEEESP-bitcoin.pdf
https://www.cs.cornell.edu/~ie53/publications/btcProcFC.pdf
https://www.econinfosec.org/archive/weis2013/papers/KrollDaveyFeltenWEIS2013.pdf
https://cseweb.ucsd.edu/~smeiklejohn/files/imc13.pdf
https://www.mercatus.org/system/files/Brito_BitcoinPrimer.pdf
https://svn.torproject.org/svn/projects/design-paper/tor-design.pdf
http://antoanthongtin.vn/Portals/0/UploadImages/kiennt2/Sach/Sach-CSDL4/D039.pdf
https://www.cs.ru.nl/~jhh/pub/secsem/chaum1985bigbrother.pdf
https://www.dfs.ny.gov/legal/regulations/adoptions/dfsp200t.pdf
https://www.tarsnap.com/scrypt/scrypt.pdf
http://www.std.org/~msm/common/memorybound.pdf
http://hashcash.org/papers/cuckoo.pdf
https://eprint.iacr.org/2013/784.pdf
http://www.dartmouth.edu/~ericz/predictionmarkets.pdf
https://mason.gmu.edu/~rhanson/PromisePredMkt.pdf
https://blockstream.com/sidechains.pdf
http://randomwalker.info/publications/namespaces.pdf
http://blockchainlab.com/pdf/Ethereum_white_paper-a_next_generation_smart_contract_and_decentralized_application_platform-vitalik-buterin.pdf
https://eprint.iacr.org/2015/702.pdf