You list different things. The 2001 reference is an ICC Specification that defines how V2 profiles are structured. The specification applies to profiles such as sRGB as well as others such as ProPhoto RGB and even printer profiles.
The 1966-2-1 is not a year. It's a profile description document number and does specify sRGB which was created jointly by HP and Microsoft.
Profile version standards are established by the ICC and ISO. These define how a given profile's internal tables should be used mathematically.
Version 2 profiles are compatible with Version 4 profiles. Version 4 sRGB profiles may, but are not required to, implement gamut mapping in Perceptual transforms but there has been no wide use of this feature so far.
You can go to www.color.org for detailed specs, white papers, and get downloadable sRGB profiles. The 1966-2-1 version dominates and is the standard in Adobe and most other products. Some manufacturers supply their own as well but all the ones I've looked at are indistinguishable outside of invisible rounding errors. One can also get at www.color.org a profile examination utility that lets you look at the guts in profiles.