The question should be a duplicate: the issue of female dwarves in Tolkien's legendarium has been discussed a lot on this site already. When I first saw it, I was going to dupehammer it closed, but the best fits I found were Is the theory that dwarf women look like dwarf men limited to the works of Tolkien? and Did Tolkien originate the idea of dwarven women as being visually indistinguishable from dwarven men? which aren't great choices since they aren't directly asking about Tolkien's legendarium.
As for the question that it was eventually closed as a duplicate of, Why didn't the dwarf women have beards in The Hobbit - An Unexpected Journey?: although the title refers only to Jackson films, the question body mentions "It's also stated by Tolkien in appendix A to The Lord of the Rings that female dwarves appear identical to males" which resolves your question. Unfortunately, the top answer is film-relevant only and you need to scroll down to the second answer to find anything about Tolkien's works.
Fortunately, I managed to find a better duplicate target: Who was the first female dwarf identified by name in the Hobbit/LOTR saga?, where both the question and the top answer are directly relevant to and almost the same as the recently-closed duplicate. I've edited the duplicate target to point to this one instead.