If you are looking to purchase these along with your lens, here are common varieties available online: VWR Lens Paper
: A professional-grade, 4x6 inch tissue often sold in packs of 50. It's designed for use with or without cleaning liquid.
Often sold in 100-sheet booklets, these are highly portable and designed specifically for DSLR lenses and eyeglasses.
Some professionals advise against cheap lens tissues, as they can sometimes trap grit and scratch delicate coatings. Many prefer high-quality microfiber cloths instead.
The "proper paper" you're looking for when buying camera lenses online likely refers to , a specialty tissue used to safely remove dust and smudges from delicate glass elements. Top Options for Lens Cleaning Paper