Most Lensed Quasars at z > 6 are Missed by Current Surveys
Fabio Pacucci and Abraham Loeb 2019 ApJL 870 L12
The discovery of the first strongly lensed quasar at z > 6 indicates the potential presence of a substantial population of lensed z > 6 quasars misclassified and mixed up with low-z galaxies.