public static IEnumerable<Resource.Citation> Citations(this Jstor.Domain.dc record) { var citations = new List<string>(); if (record.identifier == null) yield break; foreach (var identifier in record.identifier) { var id = identifier.Value.Split(' '); if (id[0] == "UID:") { var resource = new Resource(id[1]); foreach (var citation in resource.Citations()) { yield return citation; } yield break; } } }