Markus has recently published his new DSL book. This is relevant for mbeddr in several ways: first, mbeddr is used as a case study in the design part of the book as well as in part IV, which addresses the use of DSLs. Second, the book contains some detail on how to develop languages with MPS. And third, it provides a general introduction to DSLs and modular languages — which is of course central to mbeddr. The book is available in print as well as a donationware PDF. Check it out at dslbook.org.