There are many excellent books that can serve as references for cursive italic calligraphy. Some popular ones include:
Some notable subject matter experts in cursive italic calligraphy include:
Alfred Fairbank: Fairbank was a British calligrapher who specialized in cursive italic calligraphy. He is the author of "A Handwriting Manual," which is a classic reference on the subject.
Gunnlaugur SE Briem: Briem is an Icelandic calligrapher and type designer who has written extensively on cursive italic calligraphy. He has created several typefaces based on the cursive italic hand and is the author of "The New Manual of Typography," which includes a section on the subject.
Getty-Dubay: Getty-Dubay is a company that specializes in handwriting instruction materials. They have developed a system of cursive italic handwriting called "Getty-Dubay Italic Handwriting" that is widely used in schools and homeschooling.
Lloyd Reynolds: Reynolds was an American calligrapher and educator who taught at Reed College in Portland, Oregon. He was a proponent of the cursive italic hand and helped to popularize it in the United States.
Examples of their work and others can be found in calligraphy books, online resources such as blogs and videos, and in art and calligraphy exhibitions.