In pdf. form. You may have to copy and paste the link into your browser to make it work.
This paper really picks apart the effects of juglone, its production levels, area of effect, and all the possibilities of growing crops under its influence. Written with permaculture in mind.
I especially like their recommendation to plant black alder (Alnus glutinosa) as a nurse crop between your rows of black walnut. Since they’re sensitive to the allelopaths, they die out. But in the meantime you’ve grown poles for coppicing, and leave a whole stump and root system to slowly release nitrogen to the walnut crop -an excellent example of systematic development by filling niches in time.