TY - JOUR AU - V. P. Maslov TI - A criterion for discreteness of the spectrum of a Sturm–Liouville equation with an operator coefficient (apropos the article by B. M. Levitan and G. A. Suvorchenkova) JO - Funkcionalʹnyj analiz i ego priloženiâ PY - 1968 SP - 63 EP - 67 VL - 2 IS - 2 UR - http://geodesic.mathdoc.fr/item/FAA_1968_2_2_a6/ LA - ru ID - FAA_1968_2_2_a6 ER -