How to join three tables using join in entity framework?

Question

How to join three tables in entity framework, i have two different models. My logic is as follows i am bit stuck.

    public class ExtractionViewModel
    {
        public DateTime Year { get; set; }

        public int Week { get; set; }

        public DateTime Day { get; set; }

        public string Model { get; set; }
    }

 public partial class WeekDetail: IEntity
    {
        public System.Guid WeekId { get; set; }
        public int WeekNum { get; set; }
        public string Year { get; set; }
        public Nullable<int> ScheduleTotal { get; set; }
        public System.DateTime CreatedDate { get; set; }
        public string CreatedBy { get; set; }
        public System.DateTime ModifiedDate { get; set; }
        public string ModifiedBy { get; set; }
        public bool InActive { get; set; }

public IList<ExtractionViewModel> GetExtractionViewModels()
        {
            ProductionManagementEntities db = new ProductionManagementEntities();

            var scheduleList = (from s in db.Schedules
                              join w in db.WeekDetails on
                              select new ExtractionViewModel
                              {
                                Year = s.ModifiedDate,
                                Week = s.
                              }).ToList();
            return scheduleList;
        }
        public ActionResult ExportToExcel()
        {

            var v = new GridView();
           // v.DataSource = this.GetExtractionViewModels();
            v.DataBind();
            Response.ClearContent();
            Response.Buffer = true;
            Response.AddHeader("content-disposition", "attachment; filename=ExtractionRecords.xls");
            Response.ContentType = "application/ms-excel";
            Response.Charset = "";
            StringWriter objStringWriter = new StringWriter();
            HtmlTextWriter htmlTextWriter = new HtmlTextWriter(objStringWriter);
            v.RenderControl(htmlTextWriter);
            Response.Output.Write(objStringWriter.ToString());
            Response.Flush();
            Response.End();
            return View("List");
        }