This is probably the best book on how the professionals had fun building rockets back in the day. It's a gread read, and full of useful practical chemical engineering advice and cautionary tales. You might find PDFs, but you can also buy it here: https://www.amazon.com/Ignition-Informal-Propellants-Univers...

Finally back in print after 40 years!

https://www.amazon.com/Ignition-Informal-Propellants-Univers...