Lorenzo Carlucci. Worms, gaps, and hydras. Math. Log. Q., 51(4):342-350, 2005. [doi]
@article{Carlucci05, title = {Worms, gaps, and hydras}, author = {Lorenzo Carlucci}, year = {2005}, doi = {10.1002/malq.200410035}, url = {http://dx.doi.org/10.1002/malq.200410035}, researchr = {https://researchr.org/publication/Carlucci05}, cites = {0}, citedby = {0}, journal = {Math. Log. Q.}, volume = {51}, number = {4}, pages = {342-350}, }