These two books cover hundreds of studies that pour cold water on the notion that the sexes are fundamenatlly different. These can be bought on Amazon second hand quite cheaply.

Same Difference: How Gender Myths Are Hurting Our Relationships, Our Children, and Our Jobs
Rosalind Barnett, Caryl Rivers

Delusions of Gender: How Our Minds, Society, and Neurosexism Create Difference
Cordelia Fine

and if you want to get to grips with a favorite theory that many CDs want to believe in - that prenatal hormones made their brains feminine then get this book as it outlines how the notion that gender is hardwired into our brains is not supported by hundreds of studies-

Brain Storm: The Flaws in the Science of Sex Differences
Rebecca Jordan-Young

I don't think you can conduct a proper analysis of what crossdressing actually is if you dont understand what gender itself is and where it comes from. If you read these 3 books then you will comprehend crossdressing is not what most CDs want you to believe it is, or what they themselves want to belive it is, since their ideas about gender are deeply flawed and based on populist notions like men are from mars, women are from venus. Men and women are not separate species, we are the same with only minor differences in a few select areas. By and large men and women equally share the same behaviors but we are socialized to act differently to obtain the significant advantages derived from conformity.