https://www.logos.com/product/195741/the-greek-of-the-septuagint-a-supplemental-lexicon?ssi=0
I suspect it was part of the 'merger' a couple years back, and Hendrikson?
In any event, it was produced about 10 years ago, and designed to supplement BDAG for LXX words and meanings. As a result, it's neither large (5,000 entries), nor expensive ($20).
Many moons back, a fellow Logosian reviewed it ... worth reading.
https://abramkj.com/2012/07/26/review-of-the-greek-of-the-septuagint-supplemental-lexicon/
2 weeks for you to decide.
