A free service for learners of English to practise their written English. You can submit your written work and receive feedback on spelling, vocabulary, grammar and general style.With tasks for beginners, intermediate and advanced.
This site leads you through the whole process of writing different academic assignments. It offers an overview of adequate grammar and punctuation use as well as different citation styles.
Short videos with tips for academic writing by the English Language Center of the Hong Kong Polytechnic University: vocabulary and style, expressions to avoid, referencing, critical thinking and more.
This resource from Purdue University in Indiana gives extensive examples of MLA, APA, and Chicago citation styles.
The OWL exercises: grammar, punctuation, spelling, sentence structure, sentence style, and ESL (English as a second language) exercises, such as paraphrasing exercises.