This is the featurephone (S40) and dumbphone (S30) set of operating systems that Nokia owns and uses on their many, many other devices. Despite zero technical relationship between these and Symbian/S60/S^3/etc. there is much overlap in documentation. It is worth looking at the Symbian section as well. 

'''Nokia Asha''' is not an OS at all. It's a marketing name (like "Lumia") for "high end" featurephones. At launch, this was also sorta, kinda discussed as though it was an OS or GUI layer, but there was little difference between that and "normal" S40, and over time this has entirely disappeared of course. I think that it just evolved to what they now call Touch & Type.

==== UI Guidelines: ====
 * [[http://www.forum.nokia.com/info/sw.nokia.com/id/73e935fe-8b59-43b2-ab3e-1c5f763672db/Series_40_UI_Style_Guide.html|Nokia Series 40 UI Style Guide]]
 * [[http://library.forum.nokia.com/index.jsp?topic=/Design_and_User_Experience_Library/GUID-A8DF3EB8-E97C-4DA0-95F6-F464ECC995BC_cover.html|Nokia Design & User Experience Library]]
 * [[http://wiki.forum.nokia.com/index.php/Category:Mobile_Design_Patterns|Nokia Mobile Design Patterns]] A series of articles, approaching a pattern library. Note that some of these may be very familiar, as it is a wiki, so some older patterns from this book and other information posted to the wiki have been copied to here by the authors, and other users.
 * [[http://www.forum.nokia.com/Design/|Forum Nokia Design Portal]] PDF.
 * [[http://www.slideshare.net/nokia-developer/series-40-full-touch-ui-style-guide-part-1|Nokia Asha UI Guidelines]] An intro to the Asha UI... but I am pretty sure that this ended up being just "Touch and Type" S40, so the Asha name is not important for UI design/development now. 

==== Stencils & Templates: ====
 * [[http://www.forum.nokia.com/Develop/Web/Mobile_web_browsing/Web_templates/Templates_for_mobile_phones/|Templates for mobile phones]] meaning mostly S40 featurephones, but also some older S60 devices.