suggestions to read

Memczak et al. Circular RNAs are a large class of animal RNAs with regulatory potency. Nature 495 (7441): 333-8 (2013)

Jeck et al. Circular RNAs are abundant, conserved, and associated with ALU repeats. RNA 19(2):141-57 (2013)

Hansen et al. Natural RNA circles function as efficient microRNA sponges. Nature 495(7441):384-8 (2013)

Vicens and Westhof Biogenesis of Circular RNAs. Cell. 159(1)13-4 (2014)

Ashwal-Fluss et al. circRNA biogenesis competes with pre-mRNA splicing. Mol. Cell. 56(1):55-66 (2014)

Ivanov et al. Analysis of intron sequences reveals hallmarks of circular RNA biogenesis in animals. Cell Reports 10(2):170-7. (2015)

Rybak-Wolf et al. Circular RNAs in the Mammalian Brain Are Highly Abundant, Conserved, and Dynamically Expressed. Mol. Cell. 58(5):870-85 (2015)