The following is a list of echo-specific resources that I have used during my training as a resident and fellow. It is by no means exhaustive or a formal endorsement and I have no relationship with any of the authors or teams referenced below, I simply found them useful and if you are looking to deepen your knowledge or understanding they can be a good place to start. These also served as references for the construction of this webpage.
Books
Perrino and Reeves - A Practical Approach to Transesophageal Echocardiography, 4th Edition (2020)
Vegas - Perioperative Two-Dimensional Transesophagael Echocardiography, 2nd Edition (2018)
Edleman - Understanding Ultrasound Physics, 4th Edition (2012)
Chang - Critical Care Echocardiography Review (2021)
This text is effectively a question bank only and is mostly focused on transthoracic imaging as well as imaging of non-cardiac structures.
Online Resources
The Utah Anesthesia Departments Echo Site (great for lecture videos)
https://echo.anesthesia.med.utah.edu/
Echo Clip of the Day (email listserv managed by Josh Zimmerman at the University of Utah)
https://lists.hsc.utah.edu/wws/subscribe/periop-echo