Could you please kindly advice where we could find the relevant documents of public library services standard and guidelines of public library assessment,…

The following web-site contains a wealth of information concerning the Finnish library system:

http://www.libraries.fi/en-GB/

The article titled Public libraries in Finland / Ministry of Education is of special importance in terms of the guidelines set for the libraries. You should also check the following web-site: http://www.libraries.fi/info

I hope that the abovementioned web-sites will provide the information you are looking for.