add links to editions to readme

README.md

@@ -8,6 +8,19 @@ Squeak is a modern, open-source development environment for the Smalltalk progra
 
 _Squeak by Example_, intended for both students and developers, will guide you through the Smalltalk language and the Squeak environment by means of a series of examples and exercises. The book helps you getting started with an initial tour of the environment before introducing the details of the language, the standard library, the tools, and the Morphic framework.
 
+### How to get this book:
+
+[![order print from lulu](./figures/badges/lulu-print.svg)](https://www.lulu.com/shop/patrick-rein-and-christoph-thiede/squeak-by-example-60/paperback/product-8vr2j2.html) [![download free PDF](./figures/badges/download-pdf.svg)](https://github.com/hpi-swa-lab/SqueakByExample-english/releases/download/6.0/SBE-6.0.pdf)
+
+#### Overview of all editions:
+
+| Edition	| PDF	| Printed	|
+| -------	| ---	| -------	|
+| **Squeak by Example 6.0 (latest release)**	| [![PDF - 6.0](https://img.shields.io/badge/PDF-v6.0-red)](https://github.com/hpi-swa-lab/SqueakByExample-english/releases/tag/6.0)	| [![lulu](https://img.shields.io/badge/lulu-v6.0-blue)](https://www.lulu.com/shop/patrick-rein-and-christoph-thiede/squeak-by-example-60/paperback/product-8vr2j2.html)	|
+| Squeak by Example 5.3.1	| [![PDF - 5.3.1](https://img.shields.io/badge/PDF-v5.3.1-red)](https://github.com/hpi-swa-lab/SqueakByExample-english/releases/tag/5.3.1)	| _(not available)_	|
+| Original 2007 edition <br>(Andrew Black, Stéphane Ducasse, et al.)	| [![PDF](https://img.shields.io/badge/PDF-2007-red)](https://inria.hal.science/inria-00441576/document)	| [![lulu](https://img.shields.io/badge/lulu-2007-blue)](https://www.lulu.com/shop/andrew-p-black-and-damien-pollet-and-st%C3%A9phane-ducasse-and-oscar-nierstrasz/squeak-by-example/paperback/product-1mmdg6p.html)	|
+| _Latest prerelease (bleeding edge!)_	| [![PDF](https://img.shields.io/badge/PDF-preprint-orange)](https://github.com/hpi-swa-lab/SqueakByExample-english/releases)	| _(not available)_	|
+
 # Repository structure
 
 The main file is SBE.tex.  Chapters are in subdirectories.