The sine integral Si ( λ x ) and the cosine integral Ci ( λ x ) and their associated functions Si + ( λ x ) , Si − ( λ x ) , Ci + ( λ x ) , Ci − ( λ x ) are defined as locally summable functions on the real line. Some convolutions of these functions and sin ( μ x ) , sin + ( μ x ) , and sin − ( μ x ) are found.