I just read the entry on the Super-Soldier Serum http://marvel.wikia.com/Glossary:Super_Soldier_Serum and I think part of the entry is factually inaccurate.

The formula for the Super-Soldier Serum is known; it is the "composition" (I can't think of the precise term right now) of the Vita-Rays that is not known.

The Vita-Rays are needed to stabilize the treatment by the Super-Soldier Serum. The Nazi spy (I forget his name right now) in Dr. Reinstein's lab stole the S-SS formula and transmitted it to the Axis forces, but was killed before he could provide the correct "composition" of the Vita-Rays (although I believe he did communicate that Vita-Rays are necessary). There is a long and infamous list of heroes and villians alike who have tried to be injected with S-SS but with either an improper application of Vita-Rays or no Vita-Rays at all; such experiments end agonizingly and with the subject's death without exception - this is what gives Cap his rent (in the economic sense of the word) to date.

I'll try to double-check my facts and find citations for the Vita-Rays thing, but this a long-standing and firmly-entrenched part of Cap's mystique: the formula for the S-SS is well-known in certain "secret world" circles in the Marvel Universe, but there is (or was, at one point in time at least) a great deal of research to find the correct "composition" of Vita-Rays to make the S-SS stabilize and produce the desired effect in a subject.

Further discussion is welcome.