1. Serial numbers 2/1-100 (Aug 1960-Nov 1963)2. Serial numbers 2/101-199 (Nov 1963-Dec 1965)3. Serial numbers 2/203-300 (Jan 1966-Mar 1968)4. Serial numbers 2/301-435 (Mar 1968-Jan 1971)5. Serial numbers 2/436-543 (Jan 1971-Nov 1972). This correspondence is mostly with the other members of the Ed...
Serial numbers 8/1-187. These letters were initially arranged in serial number (i.e. chronological) order, but have at some point been re-ordered by Corresponding Editors. This new arrangement has been retained. See also MS 45. Language(s): Partly in Dutch, French, German or Spanish.
Serial numbers 6/1-208. In a letter of 3 May 1971 (serial no 2/448, within MS 35/5), Koeman explained that file series 6 was for 'miscellaneous subjects like translation, inquiries etc'. Language(s): Partly in Dutch, French, German or Spanish.
Serial numbers 2/549-597 (for Jan-Dec 1973), with later items unmarked. For earlier correspondence in this series, see MS 35. Language(s): Partly in German.