That's certainly a great album, but it's a rather broad question. I suppose I would start by saying that Donnie was an arranger and writer for Curtis Mayfield at the end of the 60s when he had his Curtom label. At the time, He had left the Impressions, but was still producing their records, so you may want to check out some later Impressions albums- actually, any Impressions albums are really great. The first Curtis solo album is also pretty fantastic.
Also, I personally recommend the Norman Whitfield psych-soul period at Motown with his Psychedelic Shack album for the Temptations. If you go a bit deeper, he had his own band called the Undisputed Truth that did their own versions of a lot of his songs- highly recommended if you like percolating bass, fuzz drenched wah wah and glorious vocal harmonies.
Lastly, if you love Donnie's sound, you owe it to yourself to explore Philly Soul of the early 70's- Gamble and Huff with Thom Bell arranging. You'll have to Wikipedia that as it's mostly singles (as opposed to representative albums), but Joe Simon "Drowning In The Sea Of Love" should do it for you. The O'Jays, The Chi Lites, The Delfonics, The Stylistics, The Blue Notes, Howard Tate etc. There's a great obscure band called New York City that's worth searching for. Check out
http://www.phillysoulclassics.com
And, of course, from there you should pivot into Atlantic R&B, Chess Records, Stax, The Okeh label and don't forget the Isley Bros.
