This publisher, as other publishers of subscription journals can hold the copyrights as long as he needs, (usually for 70 years) but despite the copyrights terms, there are publishers who allow posting the papers in institutional repositories.
Copyright is a complicated form of intellectual property protection.Trademarks protect the use of a mark to sell a good or service. Copyright protects something far more abstract: a creative expression. It is often very difficult to describe exactly what does and does not infringe a copyright. The legal test for infringement may rest on how similar characters in a novel are or how close one song's refrain is to another's. Copyright law applies legal tests to creative endeavor, which is also vary from countries.