I advise you read about the stages of attachment by Schaffer and Emerson, read about their study and how they did it.
Read about Bowlby's monotropic theory
Ainsworth's Strange situation
Different attachment types and how they vary across cultures
Bowlby's theory of maternal deprivation
Early attachments and adult relationships
I am not sure there are many studies which focus on child memory, but if you talk about attachment there is a lot to talk about