var doubleSided = {
  "2BN": true,
  "2CH": true,
  "2CL": true,
  "2FI": true,
  "2HT": true,
  "2RT": true,
  "3BN": true,
  "3CH": true,
  "3CL": true,
  "3FI": true,
  "3HT": true,
  "3RT": true,
  "4BN": true,
  "4CH": true,
  "4CL": true,
  "4FI": true,
  "4HT": true,
  "4RT": true,
  "TBN": true,
  "TCL": true,
  "THT": true,
  "TRT": true,
};