Getting string between strings in a line

private IEnumerable<string> GetSubStrings(string input, string start, string end)
{
   Regex r = new Regex(Regex.Escape(start) + "(.*?)" + Regex.Escape(end));
   MatchCollection matches = r.Matches(input);

         foreach (Match match in matches)
                yield return match.Groups[1].Value;
        }