Stanford University details five basic steps for getting permission: Determine if permission is needed. Identify the owner. Identify the rights needed. Contact the owner and negotiate whether payment is required. Get your permission agreement in writing.
Tulane Center for IP Law and Culture. In beta testing, this is a "software and research system that provides legal information regarding the copyright status of any work in any jurisdiction in the world." Fee for services.
Brief overview with references to the Berne Copyright Convention and the Marrakesh Treaty. This site provides current, concise information with a follow-up quiz to test your knowledge. Courses are available.
In particular see the WIPO Intellectual Property Handbook (2004) "This general reference work...covers all aspects of intellectual property (IP), including international treaties and conventions, the administration and enforcement of IP rights and WIPO's work in its Member States. Issues such as electronic commerce, biotechnology, traditional knowledge and management of copyright and related rights are also covered."