Actually, the term Syntopical was used by Mortimer Adler and Charles Van Doren, authors of How To Read A Book, first published in 1940. Their fourth level of reading was Syntopical Reading - how to read two or more books on the same topic.
Paul Scheele and Patricia Danielson borrowed the idea and began to use the term Syntopic (not Synoptic) in connection to PhotoReading, meaning to PhotoRead several books on the same subject (as mentioned above).
