Ask HN: Recommended books or resources for genuine small businesses

My wife is a bonafide small business owner. She runs an interior design business as sole proprietor with a handful 1099 contractors on staff to help with errands and junior design work.

She is at a point where her business is thriving, but she is struggling under the weight of her growing business. She is a creative. She's great at that part. My expertise is in growing startups quickly, which is frankly useless to her. At best my ideas are overkill, and it's hard for me to shift my mindset since I don't know small businesses.

Can anyone point me in the direction of some tried-and-true small business frameworks? A good book or two would go a long way.