@misc{indiciae616720224d60,
  title = {Convex programs having some linear constraints.},
  author = {R J Duffin},
  year = {1977},
  doi = {10.1073/pnas.74.1.26},
  url = {https://pubmed.ncbi.nlm.nih.gov/16592378/},
  note = {Source identifier: 16592378}
}