Visual Basic - busqueda de libro por anio

Public Type TDULibro

    titulo As String

    autor As String

    editorial As String

    comentario As String

    anio As Integer

    cantPaginas As Integer

End Type

Public libros() As TDULibro

Public Const MIN = 1

Public Const MAX = 100

Dim ValorAnoMin as Integer = CInt(textbox1.text)

Dim ValorAnoMax as Integer = CInt(textbox2.text)

If ValorAnoMin>ValorAnoMax Then

    Aquí pones un mensaje de error que te devuelva a los textbox para corregir el error

End If

If ValorAnoMax>Year(DateTime.Now) Then

    Aquí pones otro mensaje de error

End If

Public Type TDUFecha

    mes as integer

    dia as integer

    anio As Integer

End Type

Public Type TDULibro

    titulo As String

    autor As String

    editorial As String

    comentario As String

    fecha As TDUFecha

    cantPaginas As Integer

End Type

Private Function busquedaXAnio(anioMin as integer, anioMax as integer) As Integer

    Dim i As Integer

    i = LBound(libros)

    While i < UBound(libros)

        if libros(i).anio >= anioMin and libros(i).anio <= anioMax then

               busquedaXAnio = i

       end if

       i = i + 1

End Function