Guys don't be too suspicious as you are in some communist country...at least we all owes that to democracy, to be vigilant but not paranoid.
I grew with your aviation books as a hobby, starting with 'aerodynamics for naval aviators'. Now I work in flight engineering dept. I think that days when some secret services chased somebody's intelligence data are over. Long time ago intelligence agencies realized that future is in bribing gov officials to serve IA. What more I think that my country's government legally delivered all material that somebody may consider as secret to your officers.
We are in internet era, remember? Nephew of my boss, 14 year old child, got on internet all aerodynamic data for Russian most modern planes, if somebody is interested I can ask child about sustained turn g of Su-27/35 or Navy F-35, all official. Maybe problem for some enemy country is to build one Su or F, not to find their facts.
So I'm asking again: can someone recommend some book dealing with fighter performance of actual aircraft?