I'm not sure what you actually want a source for. The design I'm talking about had the booster as a giant winged and crewed spacecraft with a winged and crewed orbiter attached. That did not require computer control algorithms (although I question your claim about the algorithms not being invented until the 2010s--the Russian Buran shuttle did an uncrewed, automated mission in 1988).
https://web.archive.org/web/20200531171908/https://history.n...