Lambda LINQ Group by on Multiple columns

foreach (var blackbook in db.Table<BookRequest>().Where(x => x.WorkingListID == listId).GroupBy(x => new {  x.Title, x.Used, x.Bind, x.ISBN, x.Copyright, x.PublisherName}).Select(x => new { bTitle = x.Key.Title, bUsed = x.Key.Used, bBind = x.Key.Bind, bISBN = x.Key.ISBN, bCopyright = x.Key.Copyright, bPublisherName = x.Key.PublisherName}))
                    {
                        var title = blackbook.bTitle.Replace("\"", "\"\"").Replace("&", "").Replace("@", "");
                        if (String.IsNullOrEmpty(title)) title = "Unknown";
                        sb.AppendLine(string.Format("\"**BBS\", {0}, {1}, , ,\"{2}\", \"{3}\", {4},  \"{5}\"", blackbook.bUsed, blackbook.bBind, blackbook.bISBN, title, blackbook.bCopyright, blackbook.bPublisherName.Replace("\"", "\"\"").Replace("&", "").Replace("@", "")));
                    }