A surprisingly useful classic, plenty of sound practical advice on asana and pranayama practice. Highly recommended

A lively and fresh translation of this indispensable classic.
Other translations are available online here and here
Matthew Remski's translation is worth a read

As far as I know this is the only translation of this indispensable classic.

A concise and faithful translation of another indispensable classic.

A good translation with helpful commentaries.

This book is available as a .pdf here
Another translation is available as a .pdf here