The directional signs to motorways are white on green, whereas the directional signs on motorways are white on blue. Compare sign F31 of the Belgian Road Code in green (a directional sign to a motorway, but not on a motorway) with the other directional signs in blue (especially F15, F25, F27 and F29, all of which are also used in blue on motorways): "Code de la route - Article 71. Signaux d'indication (F1-F31)". Retrieved 28 September 2021.
Österman, Tuomas; Miettinen, Saija; Ronkainen, Kaisa (2005). "Opastusmerkkien luettavuus" [Readability of guidance signs] (PDF) (in Finnish). Helsinki: Tiehallinto. Archived from the original(PDF) on 4 March 2016. Retrieved 31 July 2011.
Österman, Tuomas; Miettinen, Saija; Ronkainen, Kaisa (2005). "Opastusmerkkien luettavuus" [Readability of guidance signs] (PDF) (in Finnish). Helsinki: Tiehallinto. Archived from the original(PDF) on 4 March 2016. Retrieved 31 July 2011.
