What has the author David G Martin written?

It appears you are referring to David Icke, a controversial British author, former professional footballer, and conspiracy theorist. While there's no record of an author named "David G Martin," David Icke is a well-known figure for his writings on conspiracy theories.

David Icke is most known for his books and lectures that:

* Promote the belief that a secret cabal of reptilian humanoids are controlling the world. He claims these reptilians are shape-shifting beings who have infiltrated positions of power and are manipulating global events.

* Question the official narrative of historical events like 9/11 and other conspiracies.

* Advocate for alternative theories and explanations that challenge mainstream views on various topics.

Some of David Icke's most popular books include:

* The Biggest Secret (1999)

* Children of the Matrix (2001)

* Human Race Get Off Your Knees: The Lion Sleeps No More (2002)

* Tales From the Time Loop (2003)

* The David Icke Guide to the Global Conspiracy (2007)

* The David Icke Guide to the Global Crisis (2009)

It's important to note that Icke's ideas are highly controversial and are widely dismissed by the scientific community and mainstream media. He has been accused of promoting antisemitism and other harmful beliefs.

If you are looking for information on David Icke, be sure to consult reputable sources and consider multiple perspectives before forming your own conclusions.