There are in all 150 psalms, not chronologically but morally divided into five books, thus:-
Book One contains Psa. 1- 41—Of these Psalms, 37 contains the name of David in the headings, and Jehovah is the characteristic Divine title throughout.
Book Two contains Psalms 42-72—All these Psalms are titled, save three, and 18 bear the name of David, while God is the characteristic Divine title.
Book Three contains Psalms 73-89—All these Psalms are headed and titled. The Divine names God and Jehovah occur in about equal numbers, although God is more prominent in the first 11 Psalms.
Book Four contains Psa. 90-106—There are only three of these Psalms titled. Jehovah is here the characteristic Divine title.
Book Five contains Psalms 107-150—Of these Psalms 16 are titled. Jehovah is the Divine name which is here almost exclusively used.