Authored by Yekutiel Yehuda Greenwald.
The "כל בו על אבלות" is a work that provides a comprehensive guide on the laws, customs, and practices related to mourning in Jewish tradition. The book offers explanations and instructions from the time a person becomes ill, through their passing, and the entire mourning period (from the moment of death through the various stages of mourning, including the shivah, shloshim, and the year of mourning).
Published in New York in 1965, it serves as a practical resource for individuals and communities observing the halachic and traditional practices associated with death and mourning. It likely covers all aspects of the process, including the proper conduct, prayers, and customs (מנהגים), with attention to both Ashkenazic and Sephardic variations where applicable.
This book would be useful for someone seeking a clear, organized presentation of the laws of mourning and how to fulfill them in a proper halachic manner.