(CBS/AP)-- The "Fifty Shades of Grey" trilogy is making lots of green.
Sales for E.L. James' erotic novels are at 10 million and counting, making it among the fastest-selling series of all time.
The explicit sensation has topped charts practically from the moment Vintage Books released it in early April. Reprints have exceeded 900,000 copies in a single day, the publisher announced Tuesday. Total sales include paperbacks, e-books and audio books. Vintage is a paperback imprint of Random House Inc.
Publishers Weekly reported that sales of "Fifty Shades of Grey" jumped 40 percent in the week before Mother's Day, as compared to the previous week, selling almost 443,000 copies.
The "Fifty Shades" books began as fan fiction, inspired by the "Twilight" series, and were a word-of-mouth hit after first being distributed in 2011 by the Australia-based Writer's Coffee Shop Publishing House.