Where do I get a ctree namespace?

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ADO.NET

Hello,
This is probably a really easy question. I am currently in the process of developing a database reader which reads information from a CTree database. I have got some code ideas upon research, but I need the

Ctree.Data.SqlClient Namespace

to begin.
I can't find this dll file when i try to add a reference? Can someone tell me how I can add this to my project?

What I have tried:

searched the reference list, could not find any.