Babbel

Teaches languages through translation and listening exercises. Also features live lessons with instructors.

Mondly

Gamifies language practice, mainly through translation and listening exercises.

Duolingo

Gamifies language practice, mainly through translation and listening exercises.

Pimsleur

Teaches languages through various methods including audio courses, flash cards, and pronunciation practice.

German: An Essential Grammar textbook grammar

Bruce Donaldson

Modern German Grammar textbook grammar

Ruth Whittle

The German Language: A Linguistic Introduction phonology grammar

Jean Boase-Beier and Ken Lodge

Modern German pronunciation textbook phonology

Christopher Hall

A Student Grammar of German textbook grammar

Paul Stocker

Basic German: A Grammar and Workbook textbook workbook grammar

Heiner Schenke, Anna Miell, Karen Seago

Intermediate German: A Grammar and Workbook textbook workbook grammar

Anna Miell and Heiner Schenke