The benefit of interleaved mathematics practice is not limited to superficially similar kinds of problems
Psychonomic Bulletin & Review (2014) - Comment
pubmed: 24578089  doi: 10.3758/s13423-014-0588-3  issn: 1531-5320  issn: 1069-9384 

Doug Rohrer, Robert F. Dedrick, Kaleena Burgess