If you can find a copy, Rugby Success starts here - by Derek Robinson, my copy is a green paperback is good for laws from iirc the mid 70s. Most of the drawings in there made they way into the first big rewrite.
Then Rugby Laws Explained, from the World Cup 1991 World Cup has the laws and detailed explanations by two of the top Scottish referees, Flemming and Anderson.
Derek Robinson also wrote A Player's Guide to the Laws in 2005 and co-wrote Better Rugby Refereeing with Ed Morrison. But I do not own either.
Most are available from second hand dealers. However, they have become collectible - so some sites want silly prices.