Copies of the memo were left on their desks by Carlos. What case of pronoun is used in the previous sentence

Which two pronouns in the paragraph have unclear antecedents? cleaning the closet yesterday i cleaned my closet and dusted it thoroughly. i found receipts in a few of my jeans. i folded them neatly and put them in my drawer. i found an old box decorated with ribbons and a pink bow. it still looked pretty and new. in the bottom drawer, there was a bottle of perfume that mom bought in sweden. the perfume is old, but it still has a fresh, flowery scent. next to the perfume there was an old postcard that dad sent when he visited china.