枚举Foreach循环c#

我试图根据用户在txtDepartment.Text中输入的文本列出一些字符串。但它显示的是我拥有的所有项目，而不仅仅是BOOK类型的项目。DEPARTMENT是一个枚举，它的值类型为BOOK、NEWSPAPER和DIGITAL。有谁知道我如何在资源列表中只显示BOOK类型而不是所有项目?下面是我到目前为止的代码:

string searchdep = txtDepartment.Text;
        foreach(Resource res in resourceslist)
        {
            if(searchdep==DEPARTMENT.BOOK)
            {
                lbResult.Items.Add(res);
            }
        }

这是我的类资源

namespace OOP_V1._3
{
    public enum DEPARTMENT
    {
       BOOK,
       NEWSPAPER,
       DIGITAL
    }
    public enum STATUS
    {
        AVALIABLE,
        BORROWED,
        RESERVED
    }
    [Serializable]
    public abstract class Resource : IComparable
    {
        public string title;
        public string refno;
        public DEPARTMENT department;
        public STATUS status;
        public string searchdep { get; set; }
        public string getTitle()
        {
            return title;
        }
        public void setTitle(string iTitle)
        {
            this.title = iTitle;
        }
        public string getRefno()
        {
            return refno;
        }
        public void setRefno(string iRefno)
        {
            this.refno = iRefno;
        }
        public DEPARTMENT getDepartment()
        {
            return department;
        }
        public void setDepartment(DEPARTMENT iDepartment)
        {
            this.department = iDepartment;
        }
        public STATUS  getStatus()
        {
            return status;
        }
        public void setStatus(STATUS iStatus)
        {
            this.status = iStatus;
        }
        public override string ToString() //display the books in the form of a string
        {
            return String.Format("Ref No: {0}, Title: {1}, Department: {2}, Status: {3}", refno, title, department, status);
        }
        public Resource(string refno, string title, string status)
        {
            this.refno = refno;
            this.title = title;
            if (status == "Available")
            {
                this.status = STATUS.AVALIABLE;
            }
            else if (status == "Borrowed")
            {
                this.status = STATUS.BORROWED;
            }
            else if (status == "Reserved")
            {
                this.status = STATUS.RESERVED;
            }
        }
        public int CompareTo(Object obj)
        {
            Resource other = (Resource)obj;
            int c = string.Compare(this.getTitle(), other.getTitle()); //comparing the title inputted by the user with a title from the list
            return c; //returning the answer
        }
    }
}

DEPARTMENT result;
if (!Enum.TryParse(searchdep, true, out result))
{
    // display error message?
    return;
}

if (result == DEPARTMENT.BOOK)
{
    foreach (Resource res in resourceslist)
    {
        lbResult.Items.Add(res);
    }
}

    static void Main(string[] args)
    {
        List<Resource> Resources = new List<Resource> { new Resource(DEPARTMENT.DIGITAL), new Resource(DEPARTMENT.BOOK) };
        List<Resource> lbResult = new List<Resource>();
        string searchdep = "BOOK";
        DEPARTMENT result;
        //if (Enum.TryParse(searchdep, true, out result))
            foreach (var res in Resources)
                if (res.department == DEPARTMENT.BOOK) //or instead == result.
                    lbResult.Add(res);
        Console.ReadLine();
    }

public class Resource : IComparable
    {
        public Resource(DEPARTMENT dep)
        {
            department = dep;
        }
         ...
    }