This double blind, placebo controlled and randomised study was conducted in Australia. It showed no superior effect for Lactobacillus reuteri on reduction of crying time compared to placebo. Its publication evoked critical responses on the selection of crying infants, which might have influenced the results of the study. These responses and comments by the investigators are found here.
Link to abstract and article: http://www.bmj.com/content/348/bmj.g2107
Sung V, Hiscock H, Tang MLK, Mensah FK, Nation ML, Satzke C, Heine RG, Stock A, Barr RG, Wake M. Treating infant colic with the probiotic Lactobacillus reuteri: double blind, placebo controlled randomised trial. Brit Med J., 2014;348:g2107.