Alabaster, C. (2010). Developing an Outstanding Core Collection: A Guide for Libraries. American Library Association.
This book, updated in 2010 from an original 2002 edition, gives step-by-step instructions on building a core collection practically from scratch and then maintaining that collection. The book is laid out in a logical order with the development of the collection including budgeting, selection, and acquisition, and the steps to maintain a collection once it has been developed including tracking, weeding, and reconsideration.
The updated version of this book is still relevant in our time though it does leave out some information about electronic resources choosing instead to focus on physical collection. The examples of core collections, mission statements, and collection development statements are great jumping off points for anyone struggling to get started with these things. Some chapters will be more relevant than others depending on the size of the library and department as some libraries have separate departments for different steps of the development process.