1988
Courant - Differential and Integral Calculus 2nd ed
    magnet:?xt=urn:btih:e0cafd8143cfc86f19bc4a045d01805b8234c465
    magnet:?xt=urn:btih:75a23824cacd69daa4c82a5d4de4155b008529cf
1985
Nikiforovskiy - Way to Integral ru
    165F3B85261FC26DE3A38B6F5F684270
    A66950B625CF09681E341BB8ADF65BC9
    D976EE3C02A6F46586A610533A69C6F1