By Collins Puzzles
By Raj Persaud
By Samantha Cartwright-Hatton
By Rubin Battino
By Alloway, Tracy Packiam
By Levitin, Daniel
By Abdullah Dougan
By Judy Parkinson
By Neil Shah
By JJ Virgin, CNS, CHFS
By Holland, Simon, Salcedo Saiz, Erica
By Jon Hanna
By Susan Gadoua, Vicki Larson
By Steven D. Levitt, Stephen J. Dubner
By Tobias Atkins, Jesse Krieger
By David DeSteno
By Haidar Bagir
By Mark Roberts, Collins GCSE
By Daniel Gilbert
By Caroline Mitchell