| Marx to Engels. 3 January |
| Engels to Jenny Marx. 3 January |
| Engels to Marx. 6 January |
| Engels to Marx. 7 January |
| Marx to Engels. 8 January |
| Marx to Engels. 8 January |
| Engels to Marx. 10 January |
| Marx to Engels, [Abstract]. 11 January |
| Marx to Ludwig Kugelmann. 11 January |
| Engels to Marx. I6 January |
| Engels to Marx. 23 January |
| Marx to Engels. 25 January |
| Marx to Ludwig Kugelmann. 30 January |
| Marx to Engels. 1 February |
| Engels to Marx. 2 February |
| Marx to Engels. 4 February |
| Engels to Marx. 11 February |
| Marx to Engels. 15 February |
| Marx to Engels. 20 February |
| Engels to Marx. 20 February |
| Engels to Marx. 1 March |
| Marx to Engels. 4 March |
| Marx to Engels. 6 March |
| Marx to Ludwig Kugelmann, [Abstract]. 6 March |
| Engels to Marx. 10 March |
| Engels to Marx. 13 March |
| Marx to Engels. 14 March |
| Marx to Engels. 16 March |
| Engels to Marx. 17 March |
| Marx to Ludwig Kugelmann. 17 March |
| Marx to Engels. 18 March |
| Engels to Marx. 19 March |
| Marx to Engels. 23 March |
| Marx to Engels, [Abstract]. 25 March |
| Engels to Marx. 29 March |
| Marx to Ludwig Kugelmann. 6 April |
| Engels to Marx. 10 April |
| Marx to Engels. 11 April |
| Marx to Laura and Paul Lafargue.
11 April |
| Engels to Marx. 17 April |
| Marx to Ludwig Kugelmann. 17 April |
| Marx to Engels. 18 April |
| Engels to Marx. 20 April |
| Marx to Engels. 21 April |
| Marx to Engels. 22 April |
| Engels to Marx. 26 April |
| Marx to Engels. 30 April |
| Marx to Engels. 4 May |
| Engels to Marx. 6 May |
| Marx to Engels. 7 May |
| Marx to Joseph Dietzgen. 9
May |
| Engels to Marx. 10 May |
| Engels to Marx. 15 May |
| Marx to Engels. 16 May |
| Engels to Marx. 22 May |
| Marx to Engels. 23 May |
| Engels to Marx. 25 May |
| Marx to Engels. 27 May |
| Marx to Engels. 20 June |
| Engels to Marx. 22 June |
| Marx to Engels. 23 June |
| Engels to Marx. 24 June |
| Marx to Engels. 24 June |
| Marx to Ludwig Kugelmann. 24 June |
| Engels to Marx. 25 June |
| Marx to Engels. 26 June |
| Engels to Marx. 26 June |
| Marx to Engels. 27 June |
| Engels to Marx. 28 June |
| Marx to Engels. 29 June |
| Marx to Engels. 2 July |
| Engels to Marx. 2 July |
| Marx to Ludwig Kugelmann. 2 July |
| Marx to Engels. 7 July |
| Engels to Marx. 4 July |
| Marx to Engels. 7 July |
| Engels to Marx. 10 July |
| Marx to Engels. 11 July |
| Engels to Ludwig Kugelmann, [Abstract]. 11 July |
| Engels to Marx. 14 July |
| Engels to Marx. 21 July |
| Marx to Engels. 23 July |
| Engels to Marx. 29 July |
| Marx to Engels. 29 July |
| Engels to Ludwig Kugelmann. 31 July |
| Marx to Engels. 4 August |
| Engels to Marx. 6 August |
| Marx to Engels. 10 August |
| Marx to Ludwig Kugelmann. 11 August |
| Marx to Friedrich Lessner. 11 August |
| Engels to Marx. 12 August |
| Marx to Engels. 13 August |
| Engels to Marx. c 14 August |
| Marx to Engels. 21 August |
| Engels to Marx. 22 August |
| Marx to Engels, [Abstract]. 26 August |
| Engels to Marx. 28 August |
| Marx to Engels. 29 August |
| Engels to Marx. 1 September |
| Marx to Engels. 9 September |
| Marx to Georg Eccarius and Friedrich Lessner. 10 September |
| Marx to Engels. 12 September |
| Marx to Sigfrid Meyer. 14 September |
| Marx to Hermann Jung. 14 September |
| Engels to Marx. 16 September |
| Marx to Engels. 16 September |
| Engels to Marx. 18 September |
| Marx to Engels. 19 September |
| Engels to Marx. 21 September |
| Marx to Engels. 23 September |
| Engels to Marx. 24 September |
| Marx to Engels. 25 September |
| Marx to Engels. 25 September |
| Engels to Marx. 25 September |
| Marx to Engels, [Abstract]. 26 September |
| Marx to Engels. 29 September |
| Engels to Marx. 30 September |
| Engels to Marx. 2 October |
| Marx to Engels. 4 October |
| Engels to Marx. 6 October |
| Marx to Nikolai Danielson. 7 October |
| Engels to Marx. 8 October |
| Marx to Engels, [Abstract]. 10 October |
| Engels to Marx. 12 October |
| Marx to Ludwig Kugelmann. 12 October [abstract] |
| Marx to Johann Baptist von Schweitzer, [Abstract]. 13 October |
| Engels to Marx. 14 October |
| Marx to Engels. 15 October |
| Marx to Hermann Jung. 19 October |
| Engels to Marx. 22 October |
| Marx to Engels. 24 October |
| Marx to Ludwig Kugelmann. 26 October |
| Engels to Marx. 28 October |
| Marx to William Jessup. 28
October |
| Marx to Sigfrid Meyer and August Vogt. 28 October |
| Marx to Bassot. 30 October |
| Marx to Engels. 4 November |
| Engels to Marx. 4 November |
| Engels to Marx, [Abstract]. 6 November |
| Marx to Engels, [Abstract]. 7 November |
| Marx to Engels. 8 November |
| Engels to Marx. 10 November |
| Engels to Marx. 13 November |
| Marx to Engels. 14 November |
| Marx to Engels. 14 November |
| Marx to Hermann Jung. 14 November |
| Marx to Engels. 18 November |
| Engels to Marx, [Abstract]. 18 November |
| Engels to Marx. 20 November |
| Marx to Engels. 23 November |
| Engels to Marx. 23 November |
| Engels to Marx. 25 November |
| Engels to W Holzenhauer. 26 November |
| Engels to Marx. 29 November |
| Marx to Engels. 30 November |
| Marx to Engels. 5 December |
| Marx to Ludwig Kugelmann. 5 December |
| Marx to Engels. 6 December |
| Engels to Marx. 8 December |
| Marx to Engels. 9 December |
| Marx to Engels. 10 December |
| Engels to Marx. 11 December |
| Marx to Engels. 12 December |
| Marx to Ludwig Kugelmann, [Abstract]. 12 December |
| Marx to Asher & Co. after 12 Dec. |
| Engels to Marx. 13 December |
| Marx to Engels. 14 December |
| Marx to Engels. 15 December |
| Engels to Marx, [Abstract]. 18 December |
| Engels to Hermann Engels. 18 December |
| Marx to Engels, [Abstract]. 19 December |
| Marx to Laura Lafargue. 22 December |
| Marx to Engels. 23 December |
| Marx to Hermann Jung. 28 December |