Key points are not available for this paper at this time.
Frits A. Goossens, Marinus H. van IJzendoorn, Quality of Infants' Attachments to Professional Caregivers: Relation to Infant-Parent Attachment and Day-Care Characteristics, Child Development, Vol. 61, No. 3 (Jun., 1990), pp. 832-837
Goossens et al. (Fri,) studied this question.