PERSI is compiled by the Allen County Public Library in Indiana, PERSI - Periodical Source Index. With 1.7 million articles in 6,000 different periodicals, PERSI is the largest index of historical and genealogical articles in the world. This index covers articles written in English and French since 1800. While you cannot access PERSI from the Allen County Public Library site, you can access it through Ancestry.com or Heritage Quest. To access it through Ancestry, go to their home page, and click on the search tab. If you scroll down, on the right hand side of the page there is a list of databases. PERSI is under the heading, "Reference & Finding Aids".
Heritage Quest is available through some public libraries. Consult your library's web site or librarian to see if they have a subscription to Heritage Quest. You can also purchase a CD of PERSI. Online retailers with copies include Ancestor Stuff at www.ancestorstuff.com.
You can search PERSI by locality or surname. It's important to note that those mentioned casually in an article will not appear in the index. For this reason it is a good idea to search both surname and locality. For example, articles listing cemetery transcriptions will be indexed under the locality, not by the individuals named in the transcription. By just conducting a surname search, you could miss out on important data.
When you search by locality you will be rewarded with anything from histories of towns and cities, to cemetery transcriptions, directories or pioneer family histories. When you search by locality you can also add a keyword. So for example I conducted a search for San Bernardino County, California and added the keyword "Mormon.". Six articles were listed regarding the colonization of San Bernardino by the Mormons. The addition of a keyword to your search can help you narrow down your search.
Once you have searched PERSI and found the articles you are interested in, you can download an order form from the Allen County Public Library web site at http://www.acpl.lib.in.us/genealogy/ArticleFulfillment.pdf. To fill out the order form you will need the name of the article, title of the journal, volume number, month and year. The cost to order articles is $7.50 per order, up to 6 articles per order form. Allen County will charge you .20 cents per page for photocopying. You can expect to receive your photocopied articles in 6-8 weeks.