how to get instances from cobweb cluster code example

Example: cobweb clustering weka

@article{Fisher1987,
    author = {D. Fisher},
    journal = {Machine Learning},
    number = {2},
    pages = {139-172},
    title = {Knowledge acquisition via incremental conceptual clustering},
    volume = {2},
    year = {1987}
 }
 
 @article{Gennari1990,
    author = {J. H. Gennari and P. Langley and D. Fisher},
    journal = {Artificial Intelligence},
    pages = {11-61},
    title = {Models of incremental concept formation},
    volume = {40},
    year = {1990}
 }