You, too, can buy the PDF pattern here and here from I Think Sew patterns. The designer has a handful of really adorable adult and baby-sized slippers. I bought this one because it looked simpler than the others. Online patterns can also be dicey, so I went for the less expensive option first.
I was really happy with the instructions, though. You get about 28 pages of instructions and pattern pieces. I've read some lukewarm-to-bad reviews of I Think Sew patterns because it's apparent that the designer/writer isn't a native English-speaker. The pattern was so well-written and specific, though, that the occasional curious phrasing didn't matter. It seemed like she was aware of this and made an extra effort to spell things out. So don't believe the hype! I Think Sew patterns are great, and I can't wait to try more of them!