Portuguese : a reference manual
Sheila R. Ackerlind and Rebecca Jones-Kellogg (2011)
A comprehensive guide for all who are interested in learning the Portuguese language and mastering its complexities.
Whilst focusing on Brazilian Portuguese, it incorporates European Portuguese variants and so provides a more complete description of the language.
It offers extensive verb charts, as well as comparisons of Portuguese with English and Spanish.
POR GRAM 12 Open access