Erik Hoffmann, Anders Walstad, Johnny Karlsson, Per-Erik Olsson, Bertil Borg. 2012. Androgen receptor-beta mRNA levels in different tissues in breeding and post-breeding male and female sticklebacks, Gasterosteus aculeatus. Reproductive Biology and Endocrinology 10: 23.

Håkan Berg, Nikolai Scherbak, Harri Liimatta, Erik Hoffmann, Johnny Karlsson, Per-Erik Olsson. 2009. Characterization of antibodies for quantitative determination of spiggin protein levels in male and female three-spined stickleback (Gasterosteus aculeatus). Reproductive Biology and Endocrinology 7: 46.

Erik Hoffmann, Anna Österman, Ian Mayer, Bertil Borg. 2008. 11-ketotestosterone is not responsible for the entire testicular effect on male reproductive behaviour in the threespine stickleback. Behaviour : 509-525.