src/HOL/Data_Structures/document/root.bib

more direct HTML presentation, without print mode;

@article{Kahrs-JFP01,author={Stefan Kahrs},title={Red-Black Trees with Types},
journal={J. Functional Programming},volume=11,number=4,pages={425-432},year=2001}

@misc{Kahrs-html,author={Stefan Kahrs},title={Red Black Trees},
note={\url{http://www.cs.ukc.ac.uk/people/staff/smk/redblack/rb.html}}}

@book{Okasaki,author={Chris Okasaki},title="Purely Functional Data Structures",
publisher="Cambridge University Press",year=1998}