Ivan N. Soskov. Second Order Definability Via enumerations. Math. Log. Q., 37(2-4):45-54, 1991. [doi]
@article{Soskov91, title = {Second Order Definability Via enumerations}, author = {Ivan N. Soskov}, year = {1991}, doi = {10.1002/malq.19910370206}, url = {http://dx.doi.org/10.1002/malq.19910370206}, researchr = {https://researchr.org/publication/Soskov91}, cites = {0}, citedby = {0}, journal = {Math. Log. Q.}, volume = {37}, number = {2-4}, pages = {45-54}, }