It's difficult for a Spanish historian avoiding an emotional identification with the topic, as you can imagine. However, there are fine works written in this country. As for the Republican leadership, Santos-Juliá (ideologically is a centrist) is an expert in the figure of Azaña, which is indispensable to understand the period. Here's an article about one of his books:
Vida y Tiempo de Manuel Azaña.
http://elpais.com/diario/2008/12/08/cultura/1228690807_850215.htmlAnother figure on the Republican side, a very controversial one, is Juan Negrin, the last PM who tried desperately to support the resistance until the end. Negrin has been very ill-treated by Francoist historians (normal) and also from left-wingers. In recent times there has been an attempt of researching more thoroughly in his figure. Though Ángel Viñas cannot be considered impartial (he tekes sides with the Republican and Negrín causes), he's a serious historian and his efforts have been notable. Another historian in a similar way is Julián Casanova. In the Foundation of Juan Negrín there's bibliography. In favour of this institution talks that
La gran Estafa: Negrín, Prieto y el Patrimonio Español by Francisco Olaya Morales is in the list.
http://www.fundacionjuannegrin.com/bibliografia.php?actual=2&id=11Personally I think that Ricardo Miralles'
Juan Negrín. La República en Guerra is a good book. Here's a review:
http://www.historiacontemporanea.ehu.es/s0021-con/es/contenidos/boletin_revista/00021_revista_hc27/es_revista/adjuntos/27_35.pdfI'm not very familiar with bibliography treating specifically the figures of Sanjurjo, Mola or Queipo de Llano. There's a book written by Gabriel Cardona, a person with a military background but opposed to Franco, with an interesting title:
A Golpes de Sable. Los grandes militares que han marcado la Historia de España. Also I've found a brief article about Mola by the same historian:
http://www.laaventuradelahistoria.es/2002/03/29/mola-el-general-que-pudo-mandar.htmlOn a footnote, Juan Vigón (minister with Franco) wrote a book called
El general Mola: el conspirador.
If you are interested in battles and military questions, I found interesting the books written by Jorge Martínez-Reverte:
La Batalla del Ebro,
La Batalla de Madrid and
La Caída de Cataluña. Martínez-Reverte has not an academic background (he's journalist) but his researches are serious and well regarded by historians, also his books on these battles are exhaustive but entertaining. As for the Battle of Madrid, he discovered some documentation that threw some light on the controversial events of Paracuellos del Jarama.
