A. A. Karatsuba, “Weighted character sums”, Izv. Math., 64:2 (2000), 249–263
Z. Kh. Rakhmonov, “A theorem on the mean value of Chebishev functions”, Russian Acad. Sci. Izv. Math., 44:3 (1995), 555–569
A. A. Karatsuba, “The distribution of pairs of quadratic residues and nonresidues of a special form”, Math. USSR-Izv., 31:2 (1988), 307–323
A. A. Karatsuba, “Estimates of character sums”, Math. USSR-Izv., 4:1 (1970), 19–29
A. A. Karatsuba, “Sums of characters over prime numbers”, Math. USSR-Izv., 4:2 (1970), 303–326