如何使用alldocs表获取SharePoint文件创建者名称?

using (SPSite site = new SPSite("http://your.sharepoint.server/"))
{
    using (SPWeb web = site.OpenWeb())
    {
        SPList list = web.Lists["Documents"];
        SPListItem item = list.Items[0];
        string author = (string)item["Author"];
        DateTime modified = (DateTime)item["Modified"];
    }
}