I can find barely any historical documentation on this subject.
If you know anything about its development, please chip in as well.
I'm writing a paper on the missions and putting them into historical context, mainly their impact on the space race.
I did a lot of Googling, and a lot of information is available on the technicalities, but nearly nothing I found puts the missions into historical context.
Even simple things such as who worked on these probes is hard to find. I believe BBC stated that this is because a lot of things were kept in secret.
However, I found and ordered a nice book - Soviet Robots in the Solar System: Mission Technologies and Discoveries
It outlines some of the key players behind the Soviet space scene, and goes a bit into internal politics and development, but nothing on secrecy or wide impact on the space race is said.
Basically at this point I'm trying to figure out why most(some of the missions were spun-off as successful even though they didn't achieve their goal.) of the info was secret and only released when USSR fell, and how everyone else reacted to the information released. I can't find which particular missions were kept in secret.
I know it's a pretty loaded question, but I just can't seem to find anything to be able to scope it down. Year ~64 onwards.