C# System.IO.Directory.GetFiles อยากทราบวิธีค้นหาไฟล์แบบ หลายนามสกุลครับ

        private void recursive(DirectoryInfo folder)
        {
            folder.GetDirectories().ToList().ForEach(f => this.recursive(f));
            folder.GetFiles().Where(f => (new string[] { "jpg", "png", "gif" }).Contains(f.Extension)).ToList().ForEach(f => f.MoveTo(string.Format(@"{0}\{1}\{2}", textBox1.Text, f.DirectoryName, f.Name)));
        }

public  static System.Collections.Generic.List<string> GetFilesRecursive(string initial,  string[] _Extension )
        {
            System.Collections.Generic.List<string> result = new System.Collections.Generic.List<string>();
            System.Collections.Generic.Stack<string> stack = new System.Collections.Generic.Stack<string>();
            stack.Push(initial);

            while ((stack.Count > 0))
            {
                string dir = stack.Pop();
                foreach (string ext in _Extension)
                {
                    string _ext = (ext.Substring(0, 1) != "*") ? "*" + ext : ext;
                    result.AddRange(System.IO.Directory.GetFiles(dir, _ext));
                }
                string directoryName = null;
                foreach (string directoryName_loopVariable in System.IO.Directory.GetDirectories(dir))
                {
                    directoryName = directoryName_loopVariable;
                    stack.Push(directoryName);
                }
            }
            return result;
        }

string[] extensions = new[] { "*.jpg", "*.png", "*.cs" };
            List<string> lst = Program.GetFilesRecursive(@"I:\DATA_CSharp_", extensions);