Friedrich W. von Henke, G. Rose, Klaus Indermark, Klaus Weihrauch. On primitive recursive wordfunctions. Computing, 15(3):217-234, 1975. [doi]
@article{HenkeRIW75, title = {On primitive recursive wordfunctions}, author = {Friedrich W. von Henke and G. Rose and Klaus Indermark and Klaus Weihrauch}, year = {1975}, doi = {10.1007/BF02242369}, url = {http://dx.doi.org/10.1007/BF02242369}, researchr = {https://researchr.org/publication/HenkeRIW75}, cites = {0}, citedby = {0}, journal = {Computing}, volume = {15}, number = {3}, pages = {217-234}, }