Bundle in MVC show error?

Question

hello guys,

please clear me thing, i am using bundles in MVC project but when i call bundle in specific view like this 

@Scripts.Render("~/bundles/switch")

it shows error 

but when i add refrence top of the view like this 

@using System.Web.Optimization

 then fine,

so here is my qustion have i to insert this refrence in all specific page. where i want to use bundle. 

 

thanks in advance