The method I followed
I attempted to write the history of Yellapus.It is not a comprehensive.It needs further eloberation.The method I followed is here under with my limitations:

The method I followed is simple. I used to collect the information from my father sri.B. Ganga Ram, uncle sri.Lakkakula Rajeshwar Rao, and other relatives. The data collection used to happen at the times of functions with relatives. Most important persons are senior citizens of the caste. To be frank, it is very much troubling with this busy job to collect data. Fortunately, I was a student of History and Telugu, with a specialization in ancient Indian history. It becomes very easy for me to refer the books relating to historical aspects and coming to logical conclusions.
I have to verify the names of the gotras and surnames. The knowledge in the languages also helped me a lot. I could deduce some information out of the surnames and gotras. The information revealed out my research has made me to write further.

In the end, I have searched the Internet to find out certain aspects such as anabheri prabhakar rao, family surnames, etc. However, I could find some deficiencies, inaccuracies in the information available in the internet about the yellapus. I have information that some people are certainly trying to build the history of Yellapus. Most unfortunately, I have no time left to discuss with them or share the information.
The way left for me is that I have to publish it first in website and seek the additional information from other people of the caste. Later I have to update the information as and when time permits and may be after publishing the two other books on other aspects.
The working and accessing of information at nirmal and Suryapet helped me a lot. My personal relations at Warangal district and north coastal area also helped me to elaborate certain aspects.
Limitations

There are no historical evidences are available about this caste such as coins, scriptures, rock edicts, etc. Even nobody has mentioned about them in their books. So,it is natural that information may be wrong to an extent.
In absence of historical evidences, I am forced to deduce certain things such as migrations, etc.,from the surnames, gotras. Some times the gotras are not relevant, as it is given to the dependents also.