How to define methods in templated abstract base class that will be used by the derived class? [duplicate]

This question already has an answer here:

• Why do I get “unresolved external symbol” errors when using templates? [duplicate] 3 answers
• Why can templates only be implemented in the header file? 15 answers

I am trying to create templated abstract base class. This class will have couple of pure virtual functions. It will also have two methods that are defined in it.

Then I derive from this templated abstract base class (I derive by specializing the template) and call those two methods that were defined in the templated abstract base class from the overloaded functions.

When I do this and try to compile I get undefined reference to. I am using cmake for building. Compilation works when I remove those two methods that were defined in base class.