This article by Martin Dunn, a former Chief Research Officer at the Land Warfare Studies Centre, poses the thought that seeking to associate Clausewitz with three levels of war is curious.

In this article via Task & Purpose, author Brad Hardy states that operational art is a cornerstone doctrinal concept that joint headquarters and defence forces use to plan everything from battalion-sized operations through to major campaigns. As such, he argues that its definition is so broad that it is vulnerable to losing its meaning.

This article by Dale Eikmeier via Small Wars Journal offers yet another perspective on whether or not the operational art is synonymous with the operational level of war. 

This article by Professor Michael Evans via the Institute for Regional Security argues that the ADF has failed to keep abreast of conceptual developments and debates regarding operational art that have occurred in peer English-speaking militaries.

To stimulate discussion and debate, authors from the Defence Studies Department, Kings College London, have put together a series of articles. In the first article via Defence in Depth, Dr Stuart Griffin argues that both the operational art and the operational level of war are still relevant.

This presentation from the former Chief of the Defence Force, Air Chief Marshall Angus Houston, outlines the senior leadership vision and joint operations out to 2030.

In this article, via Defence-In-Depth, Kings College London, two historians Dr Huw Davies and Dr Robert Foley, outline the relevance of the operational art and operational level of war concept to the Napoleonic Wars, the First World War, and the Second World War.

This document via the United States Air Force College provides a concise 1 1/2 page explanation of each of the levels and how they relate to one another.

In less than a page encyclopedia.com breaks it down for us, explaining that operational art forms a bridge between strategy, defining the political aims of a war, and tactics, fighting the battles of a war.

The book 'The Operational Art: Canadian perspectives: Context and Concepts', edited by Allan English, Daniel Gosselin, Howard Coombs and Laurence Hickey contains a number of essays that are designed to make a contribution to professional military education.