function getFormulaUrl(formula){

  let baseUrl = "https://www.ad.nl/abonnementen/ad"
  const formulas = ['AD_P', 'AD_D', 'AD_ZD', 'AD_CD'];

  if (formulas.includes(formula)) {
   return `${baseUrl}/snel-bestellen/?abo_type=${formula}`;
  }

  return baseUrl;
 }