Top of page
Skip to main content
Library of Congress
Search
Everything
Audio Recordings
Books/Printed Material
Films, Videos
Legislation
Manuscripts/Mixed Material
Maps
Notated Music
Newspapers
Periodicals
Personal Narratives
Photos, Prints, Drawings
Software, E-Resources
Web Archives
Web Pages
3D Objects
Search
Search toggle
menu
Discover
Services
Visit
Education
Connect
Shop
external link
Donate
About
Ask a Librarian
Help
Contact
Search Online Catalog
Copyright.gov
Congress.gov
Share
Book/Printed Material
Image 19 of Knotty problems,
Back to Search Results
About this Item
Image
Image w/Text
PDF
Image
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19 of 84
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
Go
Pages
Previous Page
Next Page
View
Single image
List
Gallery
Grid
Slideshow
Go
