José L. Balcázar, Ronald V. Book, Uwe Schöning. Sparse Sets, Lowness and Highness. SIAM Journal on Computing, 15(3):739-747, 1986.
@article{BalcazarBS86, title = {Sparse Sets, Lowness and Highness}, author = {José L. Balcázar and Ronald V. Book and Uwe Schöning}, year = {1986}, researchr = {https://researchr.org/publication/BalcazarBS86}, cites = {0}, citedby = {0}, journal = {SIAM Journal on Computing}, volume = {15}, number = {3}, pages = {739-747}, }