Hi Angie, I'm not aware of any articles on negative spaces and would like to know too, but to explain, you can first look at a photo in the link.
All the green spaces between the horses legs are considered negative spaces. You can use these spaces or any space or shape that appears on the outside of a subject in different ways. You can put emphasis on the negaitve space in repetition like the horses legs. The light green triangles stand out from the darks, creating some interest and rhythm in the picture. Sometimes I use negative space to judge proportion in figure drawing. If a model has her hands resting on her hips, I recheck my drawing by comparing the triangle that appears inbetween as well as the arm itself. That's just a start. I hope you find more helpful info as well as your articles. I'm sure they are around on this site somewhere. It comes in handy when drawing!