[1]Ayyad, A., Cochrane, T. and Zheng, Z., ‘The congruence
${x}_{1} {x}_{2} \equiv {x}_{3} {x}_{4} ({\rm mod} \hspace{0.334em} p)$, the equation
${x}_{1} {x}_{2} = {x}_{3} {x}_{4} $ and the mean value of character sums’, J. Number Theory 59 (1996), 398–413. [2]Boklan, K. D. and Wooley, T. D., ‘On Weyl sums for smaller exponents’, Funct. Approx. Comment. Math. 46 (2012), 91–107.
[3]Chang, M.-C., ‘An estimate of incomplete mixed character sums’, in: An Irregular Mind, Bolyai Society Mathematical Studies, 21 (Springer, Berlin, 2010), 243–250.
[4]Fouvry, É., ‘Consequences of a result of N. Katz and G. Laumon concerning trigonometric sums’, Israel J. Math. 120 (2000), 81–96.
[5]Fouvry, É. and Katz, N., ‘A general stratification theorem for exponential sums, and applications’, J. reine angew. Math. 540 (2001), 115–166.
[6]Iwaniec, H. and Kowalski, E., Analytic Number Theory (American Mathematical Society, Providence, RI, 2004).
[7]Li, W.-C. W., Number Theory with Applications (World Scientific, Singapore, 1996).
[8]Luo, W., ‘Rational points on complete intersections over
${ \mathbb{F} }_{p} $’, Int. Math. Res. Not. IMRN 1999 (1999), 901–907. [9]Shparlinski, I. E., ‘On the distribution of points on multidimensional modular hyperbolas’, Proc. Japan Acad. Ser. A Math. Sci. 83 (2007), 5–9.
[10]Shparlinski, I. E., ‘On a generalisation of a Lehmer problem’, Math. Z. 263 (2009), 619–631.
[11]Shparlinski, I. E. and Skorobogatov, A. N., ‘Exponential sums and rational points on complete intersections’, Mathematika 37 (1990), 201–208.
[12]Skorobogatov, A. N., ‘Exponential sums, the geometry of hyperplane sections, and some Diophantine problems’, Israel J. Math. 80 (1992), 359–379.
[13]Weil, A., Basic Number Theory (Springer, New York, 1974).
[14]Wooley, T. D., ‘Vinogradov’s mean value theorem via efficient congruencing, II’, Duke Math. J. 162 (4) (2013), 673–730.