I will try to relaunch this blog. I think it was a good idea and I need to practice writing. I will begin with something easy to do. I have started reading a book:
1. Einstein clock’s, Poincaré’s maps, by Peter Gallinson, 2003, Hodder and Stoughton, London.
It is an attempt to put the revision of the concept of times made by Einstein and Poincaré in its context. More precisely, it makes the connexion with the standardization of units of length, time and longitude that took place during the same period. It shows a link between theoretical considerations (making the laws of electromagnetism and the principle of relativity compatible, defining of simultaneous events…) and practical ones (measuring longitudes precisely, coordinating train schedules, synchronizing clocks…). Very interesting so far. I wanted to know more, so I gathered a few links on the history of special relativity (mostly through Wikisource). Here they are, in roughly chronological order. I have yet to read most of them.

The articles where Hendrik Antoon Lorentz introduces his famous transformations (in particular where he defines ‘local time’):
2. Simplified Theory of Electrical and Optical Phenomena in Moving Systems, by H. A. Lorentz, Proceedings of the Royal Netherlands Academy of Arts and Sciences, 1899 1: 427–442.
3. Electromagnetic phenomena in a system moving with any velocity smaller than that of light, by H. A. Lorentz, Proceedings of the Royal Netherlands Academy of Arts and Sciences, 1904, 6: 809–831.

The philosophical paper by Henri Poincaré on the measure of time (seen as a convention):
4. La Mesure du Temps, by  Henri Poincaré, Revue de métaphysique et de morale, 1898, 6: 1-13
It has been reproduced as the second chapter in his third book on the philosophy of science:
5. La Valeur de la Science, by Henri Poincaré, 1911, Flammarion, Paris.
Here is an English translation.
Poincaré also published two versions of an article on the group properties of the Lorentz transformations
6. Sur la dynamique de l’électron, by Henri Poincaré, Comptes Rendus de l’Académie des Sciences, 1905, 140: 1504–1508.
7. Sur la dynamique de l’électron, by Henri Poincaré, Rendiconti del Circolo matematico di Palermo, 1906, 21: 129–176.
Here are the English translations for 1905 and 1906.

The fundamental article by Einstein is not difficult to find. Here it is in the original German throught wikilivres.ca:
8. Zur Elektrodynamik bewegter Körper, by Albert Einstein, 1905, Annalen der Physik 322 (10): 891–921.
Here is an English translation.

As far as I know, the concept of space-time is a creation of the German mathematician Hermann Minkowski. He presented it to the public during a famous conference held at the 80th Assembly of German Natural Scientists and Physicians on September 21, 1908 in Cologne. One can find on Wikisource transcripts in the original German or translated into English. A French translation is available through the French server for mathematical documents Numdam.

I found recently a transcript of a very interesting speech by Freeman Dyson:
9. Missed opportunities, by Freeman Dyson, 1972, Bulletin of the American Mathematical Society  78 (5): 635-652.
Part of it deals with the theory of relativity. Dyson argues that if mathematics had been taken seriously, one could have realized that the Poincaré group was more natural than the Galilei group, and the de Sitter group even more natural. Thus the discovery of the curvature of space-time could have been accelerated. He refers to  a paper on group structures compatible with the requirement of space-time homogeneity, isotropy and causality, by Henri Bacry and Jean-Marc Lévy-Leblond:
10. Possible kinematics, by H. Bacry and J.-M. Lévy-Leblond, 1968, Journal of Mathematical Physics, 9: 1605-1614.
Unfortunately I could not find an online version. But I have found two more elementary papers by Lévy-Leblond on the subject:
11. One more derivation of the Lorentz transformation, Jean-Marc Lévy-Leblond, 1976, American Journal of Physics, 44 (3): 271-277.
12. Additivity, rapidity, relativity, by J.-M. Lévy-Leblond and J.-P. Provost, 1979, American Journal of Physics, 47 (12): 1045.