The "Encyclopaedia Article"
Arnold Sommerfeld (external link), who had at times dealt intensively with relativity theory, was very heavily occupied with topics connected with atomic structure and quantum theory and in 1919 assigned the writing of a paper on relativity theory for the "Encyklopädie der mathematischen Wissenschaften" to Wolfgang Pauli, who at that time was still only in his first semester.
The "Encyclopaedia Article", which ultimately assumed the scope of book running to some 250 pages, was published in 1921. To this day physicists regard it as a fundamental, well-researched and comprehensive representation of the subject. Albert Einstein was greatly influenced by it.