This work (with ISBNs: 842396812X, 8423992500, and 8467000767) is the 1999 "Ortografía" which is 162 pages and has other significant differences from the 2010 "Ortografía", which comes in at 743 pages (and has ISBNs: 8467034262, 978-8467034264, 6070706536, and 978-6070706530).

(To the combiner community: If there's a consensus that the 1999 and 2010 works should still be combined, then we should at least be consistent and also combine other works that are in the same tradition of the RAE dictating orthography rules, e.g.: Nuevas normas de prosodia y ortografía (1959), Prontuario de ortografía de la lengua castellana (1844), Orthographia española (1741).)