Reddit mentions of The Lean Toolbox: The Essential Guide to Lean Transformation

Operations Management - Nigel Slack is a well known author in this field and I've found this book helpful in my MSc. It is quite broad and covers a lot of topics. If I were to buy any book I'd buy this one (but buy it second hand unless you are rich).

If you are looking at organizational culture and behavior I can vouch for Management & Organisational Behaviour. Mastering the key models in this book will help you create a more productive and pleasant business. If you are looking at progressing into or further within a leadership role then I would definitely give this a read.

If you work in manufacturing or something a little less service based then The Lean Toolbox is an absolutely excellent guide, although the publishers really could have done with adding some colour. It was recommended to my by some consultants who used to work in Toyota's leadership. A lot of information, that is a lot of help.

If you are looking at business from a process perspective Business Process Management is quite good.

If you want a decent read, something not textbooky and more like a story then The Goal is good, but uses Goldratt's theory of constraints approach which can be viewed as a little dated in comparison with more modern business transformation philosophies. Still good though!