Edward, S., B., Kent, N., R.(1996).Fundamentals of differential equation and bondary value problems / R. Kent Nagle, Edward B. Saff (Ed.ke-2).Massachusetts:.
Gaya MLA
Saff, B., Edward., Nagle, R., Kent."Fundamentals of differential equation and bondary value problems / R. Kent Nagle, Edward B. Saff".Ed.ke-2Massachusetts:,1996.Textbook.