Register for Simple Text Query
CrossRef's Simple Text Query (http://www.crossref.org/SimpleTextQuery/), powered by eXtyles refXpress from Inera, is time-saving tool for individuals to find CrossRef DOIs for their untagged citations.
The service is intended for non-commercial use by individuals. Unfortunately, we have had many commercial organizations using STQ for bulk citation processing, substantially raising our costs.
In order that we may continue to make this valuable service available for free to individuals, we will be requiring users to sign up for an account and to provide their email addresses. This change will be implemented within the next few weeks.
Those organizations who need a way to retrieve CrossRef DOIs for commercial purposes or in quantity should contact firstname.lastname@example.org to find out about the available options.
CrossRef's Guest Query form (http://www.crossref.org/guestquery/), and our experimental CrossRef Metadata Search (http://api.labs.crossref.org/search) will continue to be available without registration.