I'm always on the hunt for new material to help me deepen my knowledge or to help me explain advanced concepts better. If you too are hungry for more info, here are some links that may be of interest.
Swing and its permutations.
Swing is a bit of an imprecise concept. If like me you've worked with African & Brazilian drummers, you'll know that it's impossible to precisely notate some of their rhythms. Some people talk about the 'African triplet' and this is a good description of that phenomenon, because African rhythms often move between straight 4/4 time and compound triple time (12/8, 6/8 etc). If you listen to transitions between the two, you'll often hear a blurring of the lines between quaver triplets and quavers ('eighth notes' for the Septics) - the hits sometimes fall outside of the 'grid' of actual notation. This is one of the elements we are referring to when we talk about 'the groove'.
But this is ALSO one of essential factors to be considered when talking about the evolution of 'jazz swing'. Of course it went through the bouillabaisse of the American tradition, mixing with many other elements to end up where it is today, but it's a good starting point if you're studying the idea.
Here are some links:
Wikepedia has a good take on it from a historical perspective: https://en.wikipedia.org/wiki/Swing_(jazz_performance_style)
Here's an interview with someone working regularly with jazz: http://jazzbackstory.blogspot.co.uk/2010/05/but-does-it-swing.html