The following paper introduces the HORST few-time signature scheme, the SPHINCS many-time signature scheme, and SPHINCS-256:

• [sphincs] 30pp. (PDF) Daniel J. Bernstein, Daira Hopwood, Andreas Hülsing, Tanja Lange, Ruben Niederhagen, Louiza Papachristodoulou, Michael Schneider, Peter Schwabe, Zooko Wilcox-O'Hearn. "SPHINCS: practical stateless hash-based signatures." Pages 368–397 in Advances in cryptology—EUROCRYPT 2015—34th annual international conference on the theory and applications of cryptographic techniques, Sofia, Bulgaria, April 26–30, 2015, proceedings, part I, edited by Elisabeth Oswald, Marc Fischlin. Lecture Notes in Computer Science 9056, Springer, 2015. ISBN 978-3-662-46799-2. Date: 2015.02.02. Supersedes: (PDF) 2014.10.01.

The following talks include information about SPHINCS:

• 2015.04.21 (PDF): Peter Schwabe, Crypto Engineering course, Radboud Universiteit Nijmegen.
• 2015.04.28 (PDF): Andreas Hülsing and Peter Schwabe, Eurocrypt 2015.