Generate all case for all letters in a word using LINQ

lettercombo.cs

void Main()
{
	string word = "abcd";
	
	List<List<string>> letters = new List<List<string>>();
	
	letters = word.ToCharArray().Select(w => new List<string>(){w.ToString().ToLower(),w.ToString().ToUpper()} ).ToList();
	
	CartesianProduct(letters)
	    .Select (x => x.Aggregate ((a,b) => a + b))
		.ToList()
		.ForEach(Console.WriteLine);
}
static IEnumerable<IEnumerable<T>> CartesianProduct<T>( IEnumerable<IEnumerable<T>> sequences)
	{
	  IEnumerable<IEnumerable<T>> emptyProduct = new[] { Enumerable.Empty<T>() };
	  return sequences.Aggregate(
	    emptyProduct,
	    (accumulator, sequence) =>
	      from accseq in accumulator
	      from item in sequence
	      select accseq.Concat(new[] {item}));
	}
// Define other methods and classes here