Diccionario panhispánico de dudas, when writing numbers more than four figures, these three will be grouped into three, starting from the right, and separating the groups by whitespace. (Exceptions: Never written with periods, commas or white separation numbers that refer to years, pages, verses, urban roads, postal codes, legal articles, decrees or laws.)
Pournader, Roozbeh (15 de outubro de 2000). «Persian decimal separator». Unicode Mail List Archive. Unicode Consortium. Consultado em 21 de junho de 2008
Röll. «Union Pacific-Eisenbahn». Enzyklopädie des Eisenbahnwesens. Consultado em 26 de agosto de 2014, entry "Union Pacific-Eisenbahn", largest numbers in table
Röll. «Bilanz». Enzyklopädie des Eisenbahnwesens. Consultado em 26 de agosto de 2014, entry "Bilanz", sums in last table
