The IPU databases are completely open and free and directly accessible from the IPU home page. Short bibliographic references are provided as well as useful links to related websites.
The three IPU databases are completely open and free, directly accessible from the IPU home page -- as for the entire site
Plain bibliographic references are usually provided, except for Parline database where also general info about legislatures and electoral systems is given
The number of links to related web sites is not so large, but they are always useful and pertinent