public ViewResult Archive(ArchiveFilter filter = ArchiveFilter.Alphabet)
{
ArchiveArticlesViewModel model = new ArchiveArticlesViewModel(null, null)
{
Filter = filter,
};
List <ArticleTitle> articles = articleRepository.GetArticlesTitles();
model.ArticlesGroups = ArticleService.GroupArticles(articles, filter);
return(View(model));
}