Since this book is primarily used in the Portuguese education system (often for 1st or 2nd cycle students), 1. Check Institutional Repositories
, though these often provide metadata rather than full-text downloads. Digital Platforms
Searching for this file is frustrating. Here is why you see broken links on blogs and file-sharing sites (RapidShare, 4shared, etc.):
If you cannot find a clean copy of the Relvas grammar, modern students often use these highly-rated alternatives: Novíssima Gramática da Língua Portuguesa by Domingos Paschoal Cegalla. Português para Provas e Concursos by Evanildo Bechara. A Gramática para Concursos Públicos by Fernando Pestana.