The production seems to have played its final performance on a Wednesday, but different sources give different info. On the one hand, The Best Plays of 1970-1971 lists a closing date of June 14, 1970, with a run of 15 performances. If correct, that would mean that the production closed on a Sunday, as might be expected for a show playing a Tuesday through Sunday schedule of performances.
Other sources, including Theatre World for the 1970-1971 season, and Variety, in its review of the show (which appeared in print after the closing), list a closing date of Wednesday, June 10, 1970, and a run of 9 performances. As the Times had no ads for the production after Sunday, June 7, it seems likely that the production did close midweek, after a run of 9 performances.
There is also some uncertainty about the number of previews the production played. Previews started on Mary 22, 1970. Both Variety and Theatre World wrote that the production played 13 previews. If it. Some Times ads indicate 14 previews, but one Times ad lists only one performance on Sunday, May 31, rather than the two generally scheduled for the production on Sundays (and listed in other ads). We are listing 13, but it may have been 14.