Graph databases

graph databases book from O'Reilly is available online in pdf form;

http://info.neotechnology.com/rs/neotechnology/images/GraphDatabases.pdf?mkt_tok=3RkMMJWWfF9wsRokv6vMZKXonjHpfsX74%2BouWaSg38431UFwdcjKPmjr1YEESMV0aPyQAgobGp5I5FEPTbPYW69ut6ULXg%3D%3D