jquery-1.5.2.js
Do you know what this file is and does? Why would one need to call a method of it on server side?
If you are talking of referencing it then you will do it on client side or one can do it on serverside using
RegisterStartUpScript[
^] OR
RegisterClientScriptBlock[
^]
Finally in case you really want to call a method of that file, then use any of the above two said methods to invoke Javascript methods from server side.