@article{bwmeta1.element.bwnjournal-article-fmv89i1p2bwm, author = {Hans Carstens}, title = {Reducing hyperarithmetic sequences}, journal = {Fundamenta Mathematicae}, volume = {89}, year = {1975}, pages = {5-11}, zbl = {0334.02023}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-fmv89i1p2bwm} }
Carstens, Hans. Reducing hyperarithmetic sequences. Fundamenta Mathematicae, Tome 89 (1975) pp. 5-11. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-fmv89i1p2bwm/