I believe that the facts given this book are true.

All the facts in this book have a in text siltation of either real slaves, slave owners or trusted libraries like the library of the Congress. If the facts were not true then he would site real people.

Also in the end of the book their is full bibliography of all the sources.

Thirdly most of the sources are trustworthy like The Library of the congress.

A lot of the facts are correct because they appear in many other sites and books.
For example the part that in a ship transporting the slaves it was so crowded that they could'nt stand is true.

Lester, Julius. To Be a Slave. New York: Scholastic, 1968.