This might help:
University of Arizona Cooperative Extension Citrus Management.
The University of Florida probably has something similar, and you might be more likely to find photos of diseases occurring in high humidity climates, which we definitely are not.
I have about 20 different citrus trees, but I've never seen that. I think you have a nutrient deficiency (I see severe chlorosis in older leaves) and possibly something else. Citrus are very heavy nitrogen, magnesium, zinc and iron feeders. Availability is highly dependent on soil pH.