Whenever a reviewer complains that the authors of a paper have failed to cite one or more relevant references, the reviewer is almost certainly right. There are so many papers published that the probability of overlooking a relevant paper approaches 1.
I just encountered such a "lost" classic. I knew that the authors of the paper had done this work, which is relevant to my research, and I have seen the key figure many times, but I discovered to my surprise that I have never actually read the paper in question:
Newell, P. T., and C.-I. Meng (1992), Mapping the dayside ionosphere to the magnetosphere according to particle precipitation characteristics, GRL 19, 609.
I've added it to the pile.