Michael Tymn has written a three-part series about ectoplasm:
Experts Discuss Ectoplasm and Materialization in Virtual Roundtable [EXTERNAL LINK]
Roundtable on Ectoplasm and Materialization Continues (Part 2) [EXTERNAL LINK]
Roundtable on Ectoplasm and Materialization Continues (Part 3) [EXTERNAL LINK]