Self publishing interview book with photos - need basic legal advice about 'release' forms

[Dan]

Hi, I am self publishing an interviews book with photos and need some basic legal advice... I have permission from all the 'interviewees' and photographers to use their photos by email message, but am a little worried that I should get signed release forms... 1, from the ‘interviewees’ to have their 'text' as well as image of them, appear in the book (kind of like a model release for a photo to be used in a magazine, etc.) and 2, from the photographers

I have about 75 'interviewees' and thus, about 75 photographers as well, from all over the world in different languages, and it will be a huge job to do this (and get them to sign it and post it back to me, since none of them are getting paid, including myself - it is an eclectic topic that serves mostly just our community and not the general public, so I doubt it will sell that many copies…)

So, I was just wondering if anyone had any advice about how 'concerned' I should be about everyone signing a release form, or is an email 'ok' good enough?

Thanks!

cheers,
Dan