Winfield Hall, From Youth Into Manhood (1909, 1918), Association Press / The International Committee of Young Men's Christian Associations (YMCA), Chapter IV and pages 29-30, 104-105. 

Sir Robert Baden-Powell, Rovering To Success 4th Impression (circa 1922), Herbert Jenkins Limited (London), p. 103-106, 121. See also Chapter V. Early editions of Rovering to Success stated that masturbation is harmful, while the later editions did not. See Robert H. MacDonald, "The Frightful Consequences of Onanism: Notes on the History of a Delusion", Journal of the History of Ideas, Volume 28, Issue 3, (1967), p. 430-431 including footnotes 30 & 35 for a discussion.

Sylvanus Stall, What A Young Boy Ought To Know (1905) [also published in 1897, 1909, 1926, 1928, 1936], The VIR Publishing Company / The John C. Winston Co, parts II and III.
Full text (1897) available free at  books.google.com (see pgs. 75-115).

Sylvanus Stall, What a Young Man Ought to Know (1936) [previously published in 1897, 1904, 1928], The VIR Publishing Company / The John C. Winston Co, p. 105-112. See also pages 60, 70-71, 75-84, 151-159.