Free Oakland City Directories are available at Internet Archive. 

City directories contain an alphabetized list of residents with their addresses, spouse’s name, profession, and often a reverse lookup by address. They often contain historical information about a locale and they’ll usually contain a separate business directory.

Free Oakland City Directories include:

• 1921 Oakland City Directory

• 1928 Oakland City Directory

• 1930 Oakland City Directory

• 1933 Oakland City Directory

• 1934 Oakland City Directory

• 1935 Oakland City Directory

• 1937 Oakland City Directory

• 1938 Oakland City Directory

• 1939 Oakland City Directory

• 1940 Oakland City Directory

• 1941 Oakland City Directory

• 1967 Oakland City Directory

• 1969 Oakland City Directory