Unable to find Microsoft.Office.Server.Search.dll

I am trying to develop a SharePoint Search Server application to run Queries through Console Application.

I need a reference to Microsoft.Office.Server.Search.dll for this to work. I tried looking for this DLL in list of Assemblies in "Add Reference" Modal. Also, based on MSDN article below, have also looked at 

%ProgramFiles%\Common Files\Microsoft Shared\web server extensions\15\ISAPI

MSDN Arcticle: http://msdn.microsoft.com/en-us/library/office/jj163300%28v=office.15%29.aspx

I am unable to find this dll in either place. Where else can I look for this DLL? Is this something we need to download?

Thanks!