The number of excellent open texts makes this another difficult category to curate. However, Introduction to Real Analysis by William Trench comes to the fore. As mentioned previously, Trench is a veteran author of high quality OER math textbooks; in this case, he has written a strong textbook with all the features one might want from a first semester real analysis text. Other textbooks in this category that should be highlighted are Elementary Real Analysis, by Brian S. Thomson, Judith B. Bruckner, and Andrew M. Bruckner; Mathematical Analysis I by Elias Zakon; Basic Analysis: Introduction to Real Analysis by Jiří Lebl; and A First Course in Complex Analysis, by Matthias Beck, Gerald Marchesi, Dennis Pixton, and Lucas Sabalka.