According to their newsletter, fellow MR member publisher ReAnimus Press are offering
Ben Bova's sf/mystery/thriller
The Multiple Man (originally published in 1976) for $0.99, DRM-free in multiple formats, through Feb 28th (technically a special deal for subscribers, but I doubt they'd object to potentially making more sales on the final day of the offer).
Use the coupon code
bova214 on the
product page here before adding to the cart.
NB: if you bought Baen's
Ben Bova Spacetime Bundle, you already have this book.
ETA: They also offer some other Bova titles and backlist releases from other sfnal authors for $3.99, which seems to be a regular price rather than an introductory sale. Here's a link to the
online version of the relevant newsletter.