Poltergeists, by Alan Gauld and A D Cornell, is back in print from White Crow Books. First published in 1979, it quickly established itself as a classic in the field.
Alan Gauld is a long-standing senior member of the SPR, as was the late Tony Cornell.
Details of the new edition of Poltergeists can be found on the White Crow Books website:
http://whitecrowbooks.com/books/page/poltergeists/
Here is Dr Gauld's page on the SPR website: