AUSTIN (KXAN) — Texas Gov. Greg Abbott is calling for a removal of “clearly pornographic” and “extremely inappropriate” books he says parents are alarmed their children have seen.

In a letter to the Texas Association of School Boards, Abbott explains that “rightfully angry parents” should be able to shield their children from public schools that “provide or promote pornographic or obscene material to students.”

Abbott doesn’t elaborate on instances where this has happened or which books/content are in question, however. Instead, he calls on districts to determine the extent to which such materials may exist and “remove them.”

In his letter, Abbott writes: “You have an obligation to Texas parents and students to ensure that no child in Texas is exposed to pornography or other inappropriate content while inside a Texas public school.”

Additionally, Abbott says schools should have increased transparency regarding in-class materials and materials available in school libraries. He also calls for increased reporting on incoming materials as they happen, or “vetting.”

While the letter doesn’t explicitly refer to it, a Texas House committee recently began an investigation into school districts and whether they carry certain titles, the Houston Chronicle reports. Books containing sexual discussion or imagery, LGBTQ identities and race are among the most questioned titles.

Committee chairperson U.S. Rep. Matt Krause, R-Fort Worth, is among the inquiry’s driving forces. Chron reports the congressman requested districts to inventory which of their books “contain material that might make students feel discomfort, guilt, anguish, or any other form of psychological distress because of their race or sex or convey that a student, by virtue of their race or sex, is inherently racist, sexist, or oppressive, whether consciously or unconsciously.”

The list contains over 800 titles.

Some of the books included on the committee’s list include the Pulitzer-prize winning book, “Stamped from the Beginning: The Definitive History of Racist Ideas in America,” by acclaimed Black author and anti-racist activist Ibram X. Kendi; several titles by best-selling LGBTQ young adult fiction author Adam Silvera; titles discussing the Black Lives Matter movement and famed novel “The Cider House Rules,” by John Irving.