@misc{indiciaed427d39e41c5,
  title = {Flexible implementations of group sequential stopping rules using constrained boundaries.},
  author = {Bart E Burington and Scott S Emerson},
  year = {2003},
  doi = {10.1111/j.0006-341x.2003.00090.x},
  url = {https://pubmed.ncbi.nlm.nih.gov/14969454/},
  note = {Source identifier: 14969454}
}