array(3) {
  [0]=>
  int(15821)
  [1]=>
  string(207) "Lin Y., Liu S., Yang H., Wu H., Jiang B. Improving stock trading decisions based on pattern recognition using machine learning technology // PLOS ONE. 2021. vol. 16. no. 8. DOI: 10.1371/journal.pone.0255558."
  [2]=>
  int(8)
}
<h1>DB Error 230: Duplicate entry '15821-8' for key 'citations.citations_submission_seq'</h1>