array(3) {
  [0]=>
  int(15821)
  [1]=>
  string(180) "Lee S.C., Eid Junio W. Portfolio construction and risk management: theory versus practice // RAUSP Management Journal. 2018. vol. 53. pp. 345–365. DOI: 10.1108/RAUSP-04-2018-009."
  [2]=>
  int(4)
}
<h1>DB Error 230: Duplicate entry '15821-4' for key 'citations.citations_submission_seq'</h1>